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Home / DTC / P1723 — Control relay - stuck

P1723 — Control relay - stuck

Detailed page for trouble code P1723.

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Code

P1723

DAEWOO P — Powertrain

Control relay - stuck

Brand: DAEWOO
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
Repair manuals

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Code

P1723

FORD P — Powertrain

Gear 3 Incorrect Ratio

Brand: FORD
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
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Code

P1723

LINCOLN P — Powertrain

Gear 3 Incorrect Ratio

Brand: LINCOLN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
166

Browse 166 LINCOLN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LINCOLN

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Code

P1723

MAZDA P — Powertrain

Gear 3 Incorrect Ratio

Brand: MAZDA
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1723

MERCURY P — Powertrain

Gear 3 incorrect Ratio

Brand: MERCURY
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
296

Browse 296 MERCURY manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCURY

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1723

Other P — Powertrain

Gear 3 incorrect Ratio

Brand: Other
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
9,546

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Code

P1723

VOLKSWAGEN P — Powertrain

Starter Interlock Circuit Open

Brand: VOLKSWAGEN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or welded relay contacts (mechanical failure)
  • Contaminated or corroded relay contacts or socket
  • Faulty relay coil or internal short
  • Poor connector or pin contact at the relay socket
  • Blown or loose fuse supplying the relay circuit
  • Short to power or ground in relay control/wiring

Symptoms

  • Check Engine light (MIL) or transmission/TC warning lamp illuminated
  • Control system affected by the relay remains powered or remains unpowered (e.g., transmission stuck in limp mode or PCM losing a circuit)
  • Erratic shifting or inability to engage gears (if relay supplies transmission control)
  • Loss of function for the circuit supplied by the relay (no power to solenoids, pumps, actuators)
  • Intermittent faults that clear after cooling or vibration
  • Persistent fault code P1723 stored in memory

What to check

  • Use a scan tool: read freeze frame and live data, confirm P1723 is current or history and note associated codes
  • Locate the specified control relay in the fuse/relay box (consult vehicle wiring/relay diagram)
  • Visually inspect the relay and socket for corrosion, heat damage, melted plastic, or burnt pins
  • Check related fuses for proper rating and continuity
  • With ignition off, gently wiggle the relay while monitoring fault for change
  • Swap the suspect relay with a known-good relay of the same type (if available) and re-check the fault

Signal parameters

  • Battery/system voltage at relay supply: typically ~11–14 V with engine off/on respectively
  • Relay control/coil command: controller should switch coil to ground or +12 V (check scan tool for commanded state)
  • Relay coil continuity: finite resistance (no open coil) when measured with multimeter
  • Relay contact/output voltage: approximately battery voltage when relay is closed, near 0 V (or open circuit) when relay is open
  • Scan-tool status for related modules (PCM/TCM) showing relay command state and any associated DTCs

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note when P1723 is active and any related transmission or power-supply codes.
  2. Consult the vehicle wiring diagram and locate the specific control relay, its fuse(s), and the control module driver circuit.
  3. Perform a visual inspection of the relay and socket for heat damage, corrosion, or foreign material. Inspect wiring harness and connector for damage or water intrusion.
  4. Check fuses serving the relay circuit for correct value and continuity. Repair or replace any blown or loose fuses.
  5. Swap the relay with a known-good unit of identical type (same part number) and clear codes. If the fault disappears, replace the relay.
  6. With the original relay removed, bench-test it: apply appropriate 12 V to coil and observe contact switching and output continuity. If it fails to switch reliably, replace the relay.
  7. Back-probe the relay socket in the vehicle: measure coil/control voltage while commanding the relay on/off with a scan tool. Confirm the controller is sending the correct command and that supply/ground are present.
  8. Measure output/contact terminal voltage under load while the relay is commanded closed to ensure the contact carries battery voltage to the load. Check for voltage drop indicating bad contact.
  9. If the relay bench-tests good and the controller command is correct, inspect and test wiring between the controller and relay for opens or shorts. Repair damaged wiring or connectors.
  10. If wiring is intact but the module does not correctly command the relay (stuck command or shorted driver), consider module-level testing or replacement per manufacturer procedures.
  11. After repairs, clear codes, perform functional tests/road test to confirm repair, and re-scan for reappearance of P1723.

Likely causes

  • Relay contacts welded closed due to arcing or overload
  • Corrosion/debris in relay socket preventing proper contact opening/closing
  • Failed relay coil causing a stuck state
  • Loose/oxidized connector pins causing intermittent stuck reading
  • Control module output transistor stuck on or shorted to supply

Fault status

⚠️ Status
P1723 — Control relay stuck: Relay contacts are not switching as commanded (stuck closed or open). Check relay, socket, fuses, wiring, and controller driver.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0700 P0705 P0750 P0562 P0563 P1682
626

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