Rear Wiper System Malfunction
Rear Wiper System Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The rear wiper motor is supplied battery positive voltage and ground. The liftgate control module controls rear wiper motor operation through the rear wiper motor speed signal circuit. The rear wiper motor speed signal circuit is supplied a battery positive reference voltage by the rear wiper motor module and is pulse width modulated to ground by the liftgate control module. The duty cycle of the pulse width modulation (PWM) determines the rear wiper motor operating mode.
Reference Information
Schematic Reference
Wiper/Washer Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Component Connector End Views)
Description and Operation
Rear Wiper/Washer System Description and Operation (Rear Wiper/Washer System Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Control Module References) for scan tool information
Circuit/System Verification
Ignition ON, command the rear wiper motor functions ON and OFF with a scan tool. If the rear wiper motor functions normal, refer to Rear Wiper Switch Circuit Test.
If the rear wiper motor can not be operated with a scan tool, refer to Rear Wiper Motor Control Circuit Test.
Circuit/System Testing
Rear Wiper Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the rear wiper washer switch.
2. Ignition ON, test for 12 volts at the 12-volt reference circuit terminal B9.
• If not the specified value, test the 12-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
3. Connect the harness connector at the rear wiper washer switch.
4. Ignition OFF, disconnect the X1 harness connector at the BCM.
5. Rear wiper switch OFF, test for 3.10K ohms between the 12-volt reference circuit terminal B9 and the signal circuit terminal B6.
• If not the specified value, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the rear wiper washer switch.
6. If all circuits test normal, test or replace the BCM.
Rear Wiper Motor Control Circuit Test
1. Ignition OFF, disconnect the harness connector at the rear wiper motor.
2. Test for less than 1.0 ohm between the ground circuit terminal A and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal C and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Connect a test lamp between the B+ circuit terminal C and the control circuit and the speed signal circuit terminal E.
5. Ignition ON, verify the brightness of the test lamp decreases gradually as the rear wiper switch is turned from OFF to 3.
• If the test lamp does not illuminate or brightness does not change, test the signal circuit for an open/high resistance, short to ground, or short to voltage. If the circuit tests normal replace the LGM.
6. If all circuits test normal, test or replace the rear wiper motor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Window Wiper and Washer Switch Replacement (Rear Window Wiper and Washer Switch Replacement)
* Rear Window Wiper Motor Replacement (Rear Window Wiper Motor Replacement)
* Control Module References (Control Module References) for BCM or LGM replacement, programming, and setup.