Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN WARNING:
On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury.
Read the HIGH-VOLTAGE SAFETY PROCEDURES. Refer to HIGH VOLTAGE SAFETY PROCEDURES .
When the HIGH-VOLTAGE POWER-DOWN PROCEDURE is necessary. Refer to VEHICLE HIGH VOLTAGE POWER DOWN .
- With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
- For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
- With the scan tool, erase all DTCs.
- Turn the ignition off for a minimum of 10.0 seconds.
- Turn the ignition on.
- Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
- With the scan tool, read DTCs.
Did the DTC return?
Yes
- Go To 2
No
- Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
- CHECK THE PARK PAWL MOTOR CONTROL OUTPUTS
- Turn the ignition on.
- Connect a volt meter between the (H159) Park Pawl Motor Control (+) circuit and the (H158) Park Pawl Motor Control (-) circuit at the Park Lock Actuator harness connector.
- With the scan tool, under EVCU, Actuators Tab, perform the Park Pawl Actuator Control function to engage the Park Pawl.
Does the volt meter show a corresponding voltage change when the Park Pawl is commanded?
Yes
- Replace the Park Lock Actuator in accordance with the Service Information. Refer to PARK LOCK ACTUATOR .
- Perform the Motor Control Processor A (MCPA) VERIFICATION TEST. Refer to MOTOR CONTROL PROCESSOR A (MCPA) VERIFICATION TEST .
No
- Check the (H159) Park Pawl Motor Control (+) circuit and the (H158) Park Pawl Motor Control (-) circuits for an open. Repair as necessary. If the circuits are OK, load test all B+, Switched Ignition and grounds to the PIM. If ok, replace the Power Inverter Module (PIM) in accordance with the Service Information. Refer to POWER INVERTER MODULE (PIM) .
- Perform the Motor Control Processor A (MCPA) VERIFICATION TEST. Refer to MOTOR CONTROL PROCESSOR A (MCPA) VERIFICATION TEST .
NO RELATED
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.