P0702 - Transmission Control System Electrical
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Transmission Control System Electrical (P0702). The module sees no circuit at all — broken wire, backed-out pin, or a failed sensor.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Transmission Control System Electrical – Coil Resistance | Resistance (Ω) | 3 - 30 Ω (typical) | Connector disconnected at 20°C |
| Transmission Control System Electrical – Duty Cycle | PWM (%) | 5 - 95 % (modulates with target) | Engine running, actuator in control |
| Transmission Control System Electrical – Supply Voltage | Voltage (V) | 11.8 - 14.4 V | Ignition ON at connector |
Connector disconnected at 20°C
Engine running, actuator in control
Ignition ON at connector
Oscilloscope Waveform Analysis
2 ms/div, 20 V/divPossible Causes
Open circuit, damaged wiring harness, or disconnected plug at Transmission Control System Electrical
Chafed or pinched wiring harness along the signal path to Transmission Control System Electrical
Internal mechanical wear or carbon deposits inside Transmission Control System Electrical
Defective internal output driver or reference circuit in the control module for Transmission Control System Electrical
Symptoms
Recommended Solution
Verify continuity (< 0.5 Ω) on the signal wire between the component plug and the ECM header connector.
Verify loaded supply voltage and harness terminal pins at Transmission Control System Electrical.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Transmission Control System Electrical.
Check supply and the low-side driver at the ECM connector. Replace the actuator or repair the circuit based on the readings.
Mechanic's Tip
Use the scan-tool output test with the scope on the control side at the same time. If duty changes but the actuator does not move, the valve is stuck — not the electrical fault you were chasing.