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
- CHECK FOR ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
- Turn the ignition on.
- Using the scan tool, read the active DTCs.
Does the scan tool display this DTC as active?
Yes
- Go to step 2
No
- If the DTC is stored, check for an intermittent condition. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out or corroded terminals.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- (W12) REAR WIPER RELAY CONTROL CIRCUIT SHORTED TO GROUND
- Turn the ignition off.
- Disconnect the Junction Block C1 harness connector.
- Measure the resistance between ground and the (W12) Rear Wiper Relay Control circuit at the Junction Block C1 harness connector.
Is the resistance below 100.0 Ohms?
Yes
- Go to step 3
No
- Replace the Junction Block in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- (W12) REAR WIPER RELAY CONTROL CIRCUIT SHORTED TO GROUND
- Disconnect the IPM C2 harness connector.
- Measure the resistance between ground and the (W12) Rear Wiper Relay Control circuit at the Junction Block C1 harness connector.
Is the resistance below 100.0 Ohms?
Yes
- Repair the (W12) Rear Wiper Relay Control circuit for a short to ground.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Go to step 4
- INTEGRATED POWER MODULE (IPM) / FRONT CONTROL MODULE (FCM)
- Reconnect the IPM C2 harness connector.
- Remove the FCM from the IPM.
- Measure the resistance between ground and the (W12) Rear Wiper Relay Control circuit at the Junction Block C1 harness connector.
Is the resistance below 100.0 Ohms?
Yes
- Replace the IPM in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Replace the FCM in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
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.
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