P072B - Stuck in Reverse
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Stuck in Reverse (P072B).
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Stuck in Reverse – Coil Resistance | Resistance (Ω) | 3 - 30 Ω (typical) | Connector disconnected at 20°C |
| Stuck in Reverse – Duty Cycle | PWM (%) | 5 - 95 % (modulates with target) | Engine running, actuator in control |
| Stuck in Reverse – 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
Chafed or pinched wiring harness along the signal path to Stuck in Reverse
Internal mechanical wear or carbon deposits inside Stuck in Reverse
Defective internal output driver or reference circuit in the control module for Stuck in Reverse
Symptoms
4
Recommended Solution
Review freeze-frame environmental data and perform fundamental voltage-drop and resistance checks on the circuit.
Verify loaded supply voltage and harness terminal pins at Stuck in Reverse.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Stuck in Reverse.
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.