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Home / DTC / P0702 — Transmission Control System Electrical

P0702 — Transmission Control System Electrical

Detailed page for trouble code P0702.

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22,461specific
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P0702

Generic P — Powertrain

Transmission Control System Electrical

Brand: Generic
Type: P — Powertrain
Views: UK: 32 EN: 54 RU: 38
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or intermittent battery voltage / weak battery
  • Poor or corroded ground(s) at transmission or control module
  • Blown fuse or faulty relay supplying the transmission control module
  • Damaged, corroded or disconnected wiring/connector to TCM or sensors
  • Faulty transmission control module (TCM) or PCM
  • Intermittent CAN bus or serial data communications

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Transmission may enter limp/limitation mode
  • Erratic shifting, harsh or delayed shifts, or failure to shift
  • Failure to engage gears or stuck in a single gear
  • Intermittent transmission operation or loss of drive
  • Possible loss of communication with transmission on scan tool

What to check

  • Retrieve freeze frame and all stored codes (scan tool) and note events/conditions
  • Verify battery state-of-charge and charging system voltage (key ON ~12.0–12.8V, engine running ~13.5–14.8V)
  • Inspect and wiggle-test wiring and connectors at the TCM and transmission for corrosion, bent pins or water
  • Check fuses and relays related to transmission control power/ignition circuits
  • Verify good chassis and engine/transmission grounds (clean and ensure tight connections)
  • Check for lost or intermittent CAN/serial communication messages with a scan tool

Signal parameters

  • Key ON battery voltage at TCM power terminal: typically ~12V (vehicle-specific)
  • Engine running charging voltage at TCM: typically ~13.5–14.8V
  • Ground resistance from TCM ground pin to chassis: ideally
  • CAN bus idle voltages (vehicle-specific): common-mode ~2.5V; CANH ~2.5–3.5V, CANL ~1.5–2.5V
  • Transmission shift solenoid coil resistance (typical range for many designs): ~6–30 Ω (check OEM spec)
  • Quiescent module current draw: small (vehicle-specific); large unexpected draw may indicate internal fault

Diagnostic algorithm

  1. Connect a full-function scan tool. Read and record all transmission and powertrain codes and freeze-frame data. Note if communication to the TCM is lost intermittently.
  2. Verify battery voltage (key ON and engine running). Charge or replace battery if low. Check charging system under load.
  3. Inspect all relevant fuses and relays for transmission control/TCM power and replace if suspect.
  4. Visually inspect TCM and transmission connectors for corrosion, bent pins, water entry, or damage. Securely reseat connectors.
  5. Back-probe the TCM power and ground pins. Confirm proper voltage and good ground while performing wiggle tests on harness to reproduce fault.
  6. Check CAN/serial communication lines with an oscilloscope or scan tool: verify idle voltages and presence of messages. Repair short/open/short-to-ground as required.
  7. Measure resistance and continuity of shift solenoids and related wiring if accessible. Compare to OEM specs and check for shorts to ground or battery.
  8. If wiring and power/ground are OK but fault persists, consider replacing or reprogramming the TCM per OEM procedure. Verify software updates and TSBs before replacement.
  9. After repairs, clear codes and perform road test to confirm fault does not return and transmission operates normally.
  10. Safety note: disconnect battery when performing high-voltage repairs or when instructed by OEM procedures. Follow lockout/tagout and proper ESD precautions for module handling.

Likely causes

  • Loose, corroded or damaged connector at the TCM
  • Low battery voltage during key on/engine start
  • Failed or intermittent TCM
  • Open or short in power/ground/communication wiring to the TCM
  • Blown fuse or bad power relay for transmission control
  • Faulty speed/position sensor causing erroneous TCM behavior

Fault status

⚠️ Status
P0702 — Transmission Control System Electrical: The control module detected an electrical fault or communication error in the transmission control system. Inspect power, ground, wiring/connectors, fuses/relays, CAN/communication and the TCM. Repair or replace affected components and confirm with a scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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Code

P0702

GWM P — Powertrain

- Electric Transmission Control System

Brand: GWM
Type: P — Powertrain
Views: UK: 19 EN: 31 RU: 32
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or intermittent battery voltage / weak battery
  • Poor or corroded ground(s) at transmission or control module
  • Blown fuse or faulty relay supplying the transmission control module
  • Damaged, corroded or disconnected wiring/connector to TCM or sensors
  • Faulty transmission control module (TCM) or PCM
  • Intermittent CAN bus or serial data communications

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Transmission may enter limp/limitation mode
  • Erratic shifting, harsh or delayed shifts, or failure to shift
  • Failure to engage gears or stuck in a single gear
  • Intermittent transmission operation or loss of drive
  • Possible loss of communication with transmission on scan tool

What to check

  • Retrieve freeze frame and all stored codes (scan tool) and note events/conditions
  • Verify battery state-of-charge and charging system voltage (key ON ~12.0–12.8V, engine running ~13.5–14.8V)
  • Inspect and wiggle-test wiring and connectors at the TCM and transmission for corrosion, bent pins or water
  • Check fuses and relays related to transmission control power/ignition circuits
  • Verify good chassis and engine/transmission grounds (clean and ensure tight connections)
  • Check for lost or intermittent CAN/serial communication messages with a scan tool

Signal parameters

  • Key ON battery voltage at TCM power terminal: typically ~12V (vehicle-specific)
  • Engine running charging voltage at TCM: typically ~13.5–14.8V
  • Ground resistance from TCM ground pin to chassis: ideally
  • CAN bus idle voltages (vehicle-specific): common-mode ~2.5V; CANH ~2.5–3.5V, CANL ~1.5–2.5V
  • Transmission shift solenoid coil resistance (typical range for many designs): ~6–30 Ω (check OEM spec)
  • Quiescent module current draw: small (vehicle-specific); large unexpected draw may indicate internal fault

Diagnostic algorithm

  1. Connect a full-function scan tool. Read and record all transmission and powertrain codes and freeze-frame data. Note if communication to the TCM is lost intermittently.
  2. Verify battery voltage (key ON and engine running). Charge or replace battery if low. Check charging system under load.
  3. Inspect all relevant fuses and relays for transmission control/TCM power and replace if suspect.
  4. Visually inspect TCM and transmission connectors for corrosion, bent pins, water entry, or damage. Securely reseat connectors.
  5. Back-probe the TCM power and ground pins. Confirm proper voltage and good ground while performing wiggle tests on harness to reproduce fault.
  6. Check CAN/serial communication lines with an oscilloscope or scan tool: verify idle voltages and presence of messages. Repair short/open/short-to-ground as required.
  7. Measure resistance and continuity of shift solenoids and related wiring if accessible. Compare to OEM specs and check for shorts to ground or battery.
  8. If wiring and power/ground are OK but fault persists, consider replacing or reprogramming the TCM per OEM procedure. Verify software updates and TSBs before replacement.
  9. After repairs, clear codes and perform road test to confirm fault does not return and transmission operates normally.
  10. Safety note: disconnect battery when performing high-voltage repairs or when instructed by OEM procedures. Follow lockout/tagout and proper ESD precautions for module handling.

Likely causes

  • Loose, corroded or damaged connector at the TCM
  • Low battery voltage during key on/engine start
  • Failed or intermittent TCM
  • Open or short in power/ground/communication wiring to the TCM
  • Blown fuse or bad power relay for transmission control
  • Faulty speed/position sensor causing erroneous TCM behavior

Fault status

⚠️ Status
P0702 — Transmission Control System Electrical: The control module detected an electrical fault or communication error in the transmission control system. Inspect power, ground, wiring/connectors, fuses/relays, CAN/communication and the TCM. Repair or replace affected components and confirm with a scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

P0700 P0705 P0715 P0720 P0750 P0740
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Code

P0702

HUMMER P — Powertrain

Transmission Control System Electrical

Brand: HUMMER
Type: P — Powertrain
Views: UK: 16 EN: 29 RU: 24
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or intermittent battery voltage / weak battery
  • Poor or corroded ground(s) at transmission or control module
  • Blown fuse or faulty relay supplying the transmission control module
  • Damaged, corroded or disconnected wiring/connector to TCM or sensors
  • Faulty transmission control module (TCM) or PCM
  • Intermittent CAN bus or serial data communications

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Transmission may enter limp/limitation mode
  • Erratic shifting, harsh or delayed shifts, or failure to shift
  • Failure to engage gears or stuck in a single gear
  • Intermittent transmission operation or loss of drive
  • Possible loss of communication with transmission on scan tool

What to check

  • Retrieve freeze frame and all stored codes (scan tool) and note events/conditions
  • Verify battery state-of-charge and charging system voltage (key ON ~12.0–12.8V, engine running ~13.5–14.8V)
  • Inspect and wiggle-test wiring and connectors at the TCM and transmission for corrosion, bent pins or water
  • Check fuses and relays related to transmission control power/ignition circuits
  • Verify good chassis and engine/transmission grounds (clean and ensure tight connections)
  • Check for lost or intermittent CAN/serial communication messages with a scan tool

Signal parameters

  • Key ON battery voltage at TCM power terminal: typically ~12V (vehicle-specific)
  • Engine running charging voltage at TCM: typically ~13.5–14.8V
  • Ground resistance from TCM ground pin to chassis: ideally
  • CAN bus idle voltages (vehicle-specific): common-mode ~2.5V; CANH ~2.5–3.5V, CANL ~1.5–2.5V
  • Transmission shift solenoid coil resistance (typical range for many designs): ~6–30 Ω (check OEM spec)
  • Quiescent module current draw: small (vehicle-specific); large unexpected draw may indicate internal fault

Diagnostic algorithm

  1. Connect a full-function scan tool. Read and record all transmission and powertrain codes and freeze-frame data. Note if communication to the TCM is lost intermittently.
  2. Verify battery voltage (key ON and engine running). Charge or replace battery if low. Check charging system under load.
  3. Inspect all relevant fuses and relays for transmission control/TCM power and replace if suspect.
  4. Visually inspect TCM and transmission connectors for corrosion, bent pins, water entry, or damage. Securely reseat connectors.
  5. Back-probe the TCM power and ground pins. Confirm proper voltage and good ground while performing wiggle tests on harness to reproduce fault.
  6. Check CAN/serial communication lines with an oscilloscope or scan tool: verify idle voltages and presence of messages. Repair short/open/short-to-ground as required.
  7. Measure resistance and continuity of shift solenoids and related wiring if accessible. Compare to OEM specs and check for shorts to ground or battery.
  8. If wiring and power/ground are OK but fault persists, consider replacing or reprogramming the TCM per OEM procedure. Verify software updates and TSBs before replacement.
  9. After repairs, clear codes and perform road test to confirm fault does not return and transmission operates normally.
  10. Safety note: disconnect battery when performing high-voltage repairs or when instructed by OEM procedures. Follow lockout/tagout and proper ESD precautions for module handling.

Likely causes

  • Loose, corroded or damaged connector at the TCM
  • Low battery voltage during key on/engine start
  • Failed or intermittent TCM
  • Open or short in power/ground/communication wiring to the TCM
  • Blown fuse or bad power relay for transmission control
  • Faulty speed/position sensor causing erroneous TCM behavior

Fault status

⚠️ Status
P0702 — Transmission Control System Electrical: The control module detected an electrical fault or communication error in the transmission control system. Inspect power, ground, wiring/connectors, fuses/relays, CAN/communication and the TCM. Repair or replace affected components and confirm with a scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

P0700 P0705 P0715 P0720 P0750 P0740
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HUMMER

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Code

P0702

LAND ROVER P — Powertrain

electric transmission control system

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 20 EN: 29 RU: 25
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or intermittent battery voltage / weak battery
  • Poor or corroded ground(s) at transmission or control module
  • Blown fuse or faulty relay supplying the transmission control module
  • Damaged, corroded or disconnected wiring/connector to TCM or sensors
  • Faulty transmission control module (TCM) or PCM
  • Intermittent CAN bus or serial data communications

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Transmission may enter limp/limitation mode
  • Erratic shifting, harsh or delayed shifts, or failure to shift
  • Failure to engage gears or stuck in a single gear
  • Intermittent transmission operation or loss of drive
  • Possible loss of communication with transmission on scan tool

What to check

  • Retrieve freeze frame and all stored codes (scan tool) and note events/conditions
  • Verify battery state-of-charge and charging system voltage (key ON ~12.0–12.8V, engine running ~13.5–14.8V)
  • Inspect and wiggle-test wiring and connectors at the TCM and transmission for corrosion, bent pins or water
  • Check fuses and relays related to transmission control power/ignition circuits
  • Verify good chassis and engine/transmission grounds (clean and ensure tight connections)
  • Check for lost or intermittent CAN/serial communication messages with a scan tool

Signal parameters

  • Key ON battery voltage at TCM power terminal: typically ~12V (vehicle-specific)
  • Engine running charging voltage at TCM: typically ~13.5–14.8V
  • Ground resistance from TCM ground pin to chassis: ideally
  • CAN bus idle voltages (vehicle-specific): common-mode ~2.5V; CANH ~2.5–3.5V, CANL ~1.5–2.5V
  • Transmission shift solenoid coil resistance (typical range for many designs): ~6–30 Ω (check OEM spec)
  • Quiescent module current draw: small (vehicle-specific); large unexpected draw may indicate internal fault

Diagnostic algorithm

  1. Connect a full-function scan tool. Read and record all transmission and powertrain codes and freeze-frame data. Note if communication to the TCM is lost intermittently.
  2. Verify battery voltage (key ON and engine running). Charge or replace battery if low. Check charging system under load.
  3. Inspect all relevant fuses and relays for transmission control/TCM power and replace if suspect.
  4. Visually inspect TCM and transmission connectors for corrosion, bent pins, water entry, or damage. Securely reseat connectors.
  5. Back-probe the TCM power and ground pins. Confirm proper voltage and good ground while performing wiggle tests on harness to reproduce fault.
  6. Check CAN/serial communication lines with an oscilloscope or scan tool: verify idle voltages and presence of messages. Repair short/open/short-to-ground as required.
  7. Measure resistance and continuity of shift solenoids and related wiring if accessible. Compare to OEM specs and check for shorts to ground or battery.
  8. If wiring and power/ground are OK but fault persists, consider replacing or reprogramming the TCM per OEM procedure. Verify software updates and TSBs before replacement.
  9. After repairs, clear codes and perform road test to confirm fault does not return and transmission operates normally.
  10. Safety note: disconnect battery when performing high-voltage repairs or when instructed by OEM procedures. Follow lockout/tagout and proper ESD precautions for module handling.

Likely causes

  • Loose, corroded or damaged connector at the TCM
  • Low battery voltage during key on/engine start
  • Failed or intermittent TCM
  • Open or short in power/ground/communication wiring to the TCM
  • Blown fuse or bad power relay for transmission control
  • Faulty speed/position sensor causing erroneous TCM behavior

Fault status

⚠️ Status
P0702 — Transmission Control System Electrical: The control module detected an electrical fault or communication error in the transmission control system. Inspect power, ground, wiring/connectors, fuses/relays, CAN/communication and the TCM. Repair or replace affected components and confirm with a scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

P0700 P0705 P0715 P0720 P0750 P0740
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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

P0702

MERCEDES-BENZ P — Powertrain

Transmission Control System Electrical

Brand: MERCEDES-BENZ
Type: P — Powertrain
Views: UK: 27 EN: 37 RU: 34
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Low or intermittent battery voltage / weak battery
  • Poor or corroded ground(s) at transmission or control module
  • Blown fuse or faulty relay supplying the transmission control module
  • Damaged, corroded or disconnected wiring/connector to TCM or sensors
  • Faulty transmission control module (TCM) or PCM
  • Intermittent CAN bus or serial data communications

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Transmission may enter limp/limitation mode
  • Erratic shifting, harsh or delayed shifts, or failure to shift
  • Failure to engage gears or stuck in a single gear
  • Intermittent transmission operation or loss of drive
  • Possible loss of communication with transmission on scan tool

What to check

  • Retrieve freeze frame and all stored codes (scan tool) and note events/conditions
  • Verify battery state-of-charge and charging system voltage (key ON ~12.0–12.8V, engine running ~13.5–14.8V)
  • Inspect and wiggle-test wiring and connectors at the TCM and transmission for corrosion, bent pins or water
  • Check fuses and relays related to transmission control power/ignition circuits
  • Verify good chassis and engine/transmission grounds (clean and ensure tight connections)
  • Check for lost or intermittent CAN/serial communication messages with a scan tool

Signal parameters

  • Key ON battery voltage at TCM power terminal: typically ~12V (vehicle-specific)
  • Engine running charging voltage at TCM: typically ~13.5–14.8V
  • Ground resistance from TCM ground pin to chassis: ideally
  • CAN bus idle voltages (vehicle-specific): common-mode ~2.5V; CANH ~2.5–3.5V, CANL ~1.5–2.5V
  • Transmission shift solenoid coil resistance (typical range for many designs): ~6–30 Ω (check OEM spec)
  • Quiescent module current draw: small (vehicle-specific); large unexpected draw may indicate internal fault

Diagnostic algorithm

  1. Connect a full-function scan tool. Read and record all transmission and powertrain codes and freeze-frame data. Note if communication to the TCM is lost intermittently.
  2. Verify battery voltage (key ON and engine running). Charge or replace battery if low. Check charging system under load.
  3. Inspect all relevant fuses and relays for transmission control/TCM power and replace if suspect.
  4. Visually inspect TCM and transmission connectors for corrosion, bent pins, water entry, or damage. Securely reseat connectors.
  5. Back-probe the TCM power and ground pins. Confirm proper voltage and good ground while performing wiggle tests on harness to reproduce fault.
  6. Check CAN/serial communication lines with an oscilloscope or scan tool: verify idle voltages and presence of messages. Repair short/open/short-to-ground as required.
  7. Measure resistance and continuity of shift solenoids and related wiring if accessible. Compare to OEM specs and check for shorts to ground or battery.
  8. If wiring and power/ground are OK but fault persists, consider replacing or reprogramming the TCM per OEM procedure. Verify software updates and TSBs before replacement.
  9. After repairs, clear codes and perform road test to confirm fault does not return and transmission operates normally.
  10. Safety note: disconnect battery when performing high-voltage repairs or when instructed by OEM procedures. Follow lockout/tagout and proper ESD precautions for module handling.

Likely causes

  • Loose, corroded or damaged connector at the TCM
  • Low battery voltage during key on/engine start
  • Failed or intermittent TCM
  • Open or short in power/ground/communication wiring to the TCM
  • Blown fuse or bad power relay for transmission control
  • Faulty speed/position sensor causing erroneous TCM behavior

Fault status

⚠️ Status
P0702 — Transmission Control System Electrical: The control module detected an electrical fault or communication error in the transmission control system. Inspect power, ground, wiring/connectors, fuses/relays, CAN/communication and the TCM. Repair or replace affected components and confirm with a scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

P0700 P0705 P0715 P0720 P0750 P0740
610

Browse 610 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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