Transmission Control System Electrical
P0702 indicates an electrical fault in the transmission control system that prevents proper communication or operation of transmission control circuits. The engine control module has detected an electrical problem such as an open circuit, short circuit, or controller malfunction, causing the transmission to enter limp mode with increased pump pressure.
What You Might Notice
- Harsh or delayed transmission shifts
- Transmission stuck in one gear or limp mode
- Reduced fuel economy
- Check engine light illuminated
- Transmission overheating due to increased pump pressure
Most Common Causes
- 1
Transmission sensor failure
Speed sensors, pressure sensors, or temperature sensors in the transmission control system may fail due to wear, contamination, or electrical degradation, preventing the PCM from receiving accurate transmission data.
- 2
Open or shorted wiring in transmission control circuits
Broken, corroded, or damaged wires in the transmission harness or connectors can interrupt electrical signals between the transmission control module and sensors, triggering this code.
- 3
Defective transmission control module or PCM
The transmission control module or engine control module may have internal circuit failures, software corruption, or programming errors that prevent proper transmission system communication.
- 4
Contaminated or burned transmission fluid
Degraded transmission fluid can cause sensor malfunction and electrical contact corrosion within solenoids and electrical components of the transmission control system.
How to Diagnose It
- 1
Check Transmission sensor failure — Speed sensors, pressure sensors, or temperature sensors in the transmission control system may fail due to wear, contamination, or electrical degradation, preventing the PCM from receiving accurate transmission data.
- 2
Check Open or shorted wiring in transmission control circuits — Broken, corroded, or damaged wires in the transmission harness or connectors can interrupt electrical signals between the transmission control module and sensors, triggering this code.
- 3
Check Defective transmission control module or PCM — The transmission control module or engine control module may have internal circuit failures, software corruption, or programming errors that prevent proper transmission system communication.
- 4
Check Contaminated or burned transmission fluid — Degraded transmission fluid can cause sensor malfunction and electrical contact corrosion within solenoids and electrical components of the transmission control system.
How to Fix It
- 1
Scan and retrieve all transmission codes
Use a diagnostic scanner to pull all stored and pending transmission control codes to identify the specific electrical fault location. This will guide diagnosis toward sensors, wiring, or control modules.
- 2
Inspect and repair transmission wiring and connectors
Visually inspect all transmission control system wiring harnesses and connectors for corrosion, damage, or loose connections. Repair or replace corroded connectors and damaged wires, and ensure all connections are secure.
- 3
Test and replace transmission sensors
Test transmission speed sensors, pressure sensors, and temperature sensors with a multimeter for proper resistance and continuity. Replace any failing sensors that do not meet manufacturer specifications.
- 4
Replace or reprogram transmission control module or PCM
If all sensors and wiring are functioning correctly, the transmission control module or engine control module may require reprogramming or replacement. This should only be performed by a qualified technician with access to proper diagnostic equipment.
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