Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P1800 — TCM Power Control Relay Circuit Open

P1800 — TCM Power Control Relay Circuit Open

Detailed page for trouble code P1800.

33,851codes
59brands
11,390generic
22,461specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P1800

BUICK P — Powertrain

TCM Power Control Relay Circuit Open

Brand: BUICK
Type: P — Powertrain
Views: UK: 21 EN: 39 RU: 32
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

CADILLAC P — Powertrain

TCM Power Control Relay Circuit Open

Brand: CADILLAC
Type: P — Powertrain
Views: UK: 18 EN: 44 RU: 33
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

CHEVROLET P — Powertrain

TCM Power Control Relay Circuit Open

Brand: CHEVROLET
Type: P — Powertrain
Views: UK: 17 EN: 44 RU: 30
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

Generic P — Powertrain

Transmission Clutch Interlock Safety Switch Circuit Failure

Brand: Generic
Type: P — Powertrain
Views: UK: 26 EN: 48 RU: 36
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

GM P — Powertrain

TCM Power Control Relay Circuit Open

Brand: GM
Type: P — Powertrain
Views: UK: 15 EN: 39 RU: 34
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

GMC P — Powertrain

TCM Power Control Relay Circuit Open

Brand: GMC
Type: P — Powertrain
Views: UK: 18 EN: 44 RU: 30
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

HUMMER P — Powertrain

TCM Power Relay Control Circuit

Brand: HUMMER
Type: P — Powertrain
Views: UK: 12 EN: 30 RU: 26
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
HTML Workshop Manuals AI manual library for HUMMER Click to show available manuals 8

HUMMER 2010 Hummer H3 Alpha

HTML Manual
Hummer H3 Alpha Years: 2010 Manual in English Sections: 37,470 AI chunks: 37,470
Short description
HUMMER · Hummer H3 Alpha · 2010
Open manual

HUMMER 2010 Hummer H3 Base

HTML Manual
Hummer H3 Base Years: 2010 Manual in English Sections: 37,150 AI chunks: 37,150
Short description
HUMMER · Hummer H3 Base · 2010
Open manual

HUMMER 2010 Hummer H3 Base

HTML Manual
Hummer H3 Base Years: 2010 Manual in English Sections: 37,523 AI chunks: 37,523
Short description
HUMMER · Hummer H3 Base · 2010
Open manual

HUMMER 2010 Hummer H3 L5-3 3.7L

HTML Manual
Hummer H3 L5-3 Years: 2010 Manual in English Sections: 14,383 AI chunks: 14,383
Short description
HUMMER · Hummer H3 L5-3 · 2010 · 3.7L
Open manual

HUMMER 2010 Hummer H3 V8-5 V8-5.3L

HTML Manual
Hummer H3 V8-5 Years: 2010 Manual in English Sections: 14,606 AI chunks: 14,606
Short description
HUMMER · Hummer H3 V8-5 · 2010 · V8-5.3L
Open manual

HUMMER 2010 Hummer H3T Alpha

HTML Manual
Hummer H3T Alpha Years: 2010 Manual in English Sections: 37,368 AI chunks: 37,368
Short description
HUMMER · Hummer H3T Alpha · 2010
Open manual

HUMMER 2010 Hummer H3T Base

HTML Manual
Hummer H3T Base Years: 2010 Manual in English Sections: 37,048 AI chunks: 37,048
Short description
HUMMER · Hummer H3T Base · 2010
Open manual

HUMMER 2010 Hummer H3T Base

HTML Manual
Hummer H3T Base Years: 2010 Manual in English Sections: 37,425 AI chunks: 37,425
Short description
HUMMER · Hummer H3T Base · 2010
Open manual
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

MITSUBISHI P — Powertrain

Automated-M/T fail(relay OFF)

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 12 EN: 28 RU: 22
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

OLDSMOBILE P — Powertrain

TCM Power Control Relay Circuit Open

Brand: OLDSMOBILE
Type: P — Powertrain
Views: UK: 30 EN: 44 RU: 30
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

Other P — Powertrain

Transmission Clutch Interlock Safety Switch Circuit Failure

Brand: Other
Type: P — Powertrain
Views: UK: 24 EN: 50 RU: 32
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1800

SATURN P — Powertrain

TCM Power Control Relay Circuit Open

Brand: SATURN
Type: P — Powertrain
Views: UK: 21 EN: 39 RU: 30
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for TCM/relay supply
  • Faulty TCM power control relay
  • Open or corroded wiring between fuse, relay and TCM
  • Poor or disconnected relay/TCM connector pins
  • Faulty body/engine control module that drives the relay
  • Internal fault in the TCM

Symptoms

  • Transmission warning light or MIL illuminated
  • Transmission may fail to engage or operate (no shift or limp mode)
  • Loss of shift control or limited gear selection
  • Multiple transmission-related DTCs logged
  • Engine may run but transmission behaves as if unpowered

What to check

  • Read and record all stored codes and freeze frame data with a scan tool
  • Check battery voltage (should be ~12.4–13.8 V with key on and engine off)
  • Inspect related fuses and fusible links for continuity
  • Visually inspect relay, relay socket and wiring for corrosion, damage or loose terminals
  • Check for corrosion/damage at the TCM connector and ground points
  • Confirm whether the relay coil receives a control voltage when ignition is ON (backprobe safely)

Signal parameters

  • Battery/supply voltage at relay supply terminal: ~12 V (key ON or start as applicable)
  • Relay coil control voltage: 12 V (or ground depending on design) when relay is commanded ON
  • Relay coil resistance: typically low ohms (check service manual for exact), continuity present across coil when not energized
  • Voltage at TCM power feed pin: battery voltage present when relay is closed; near 0 V when open

Diagnostic algorithm

  1. Safety first: park vehicle, set parking brake, turn ignition OFF and disconnect negative battery terminal if required before disconnecting connectors
  2. Connect a scan tool, note P1800 and any related codes, clear codes and attempt to re-create with ignition ON/engine running as required
  3. Visually inspect and test the fuse(s) for the TCM/relay circuit; replace any blown fuse and retest
  4. Locate the TCM power control relay and inspect socket/terminals for corrosion or looseness; swap with identical relay to confirm function
  5. With ignition ON (engine off) backprobe relay coil terminals: verify control side is being driven (12 V or ground) when scan tool requests TCM power; if no drive, trace to the module that controls the relay
  6. Measure battery voltage at relay supply terminal and at the relay output (feed to TCM) with relay energized; if supply is present but no output when relay is energized, replace relay
  7. If relay output is present but TCM still not powered, check continuity from relay output to TCM power pin and inspect TCM connector, repair any open/corroded wiring
  8. If wiring checks OK and relay operation is correct but code persists, test/replace the module that commands the relay (refer to vehicle wiring diagram) or consider TCM internal fault and follow manufacturer procedures for TCM testing/replacement

Likely causes

  • Faulty or stuck open TCM power relay
  • Open circuit in relay supply or relay coil control wire
  • Blown related fuse or fusible link
  • Corroded/loose connector at relay or TCM harness

Fault status

⚠️ Status
Open circuit detected in TCM power control relay circuit — TCM may lose power or not initialize. Check relay, fuse, wiring and connectors for open or high-resistance conditions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0641 P0615 P0562 P0563 P0616
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .