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Rear Wiper System Malfunction



Rear Wiper System Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



Diagnostic Fault Information






Circuit/System Description

The wiper washer switch is mounted on the (SWM). The SWM recieves inputs from the windshield wiper switch to determine rear wiper state. The Underhood Electrical Center (UEC) controls the wiper motor based on LS CAN messagesit recieves from the Steering Wheel Module. When the UEC recieves a request for rear wipers it sends a LS CAN message to the Rear Electrical Center (REC) to activate the rear wipers


The REC controls the rear wiper motor through a PCB relay that is part of the REC..


Reference Information
Schematic Reference

Wiper/Washer Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Wiper/Washer System Description and Operation (Wiper/Washer System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool Information


Circuit/System Verification

1. Ignition ON, wiper switch in the OFF position, verify the scan tool Windshield Washer Switch parameter is Inactive.

• If not the specified value, refer to Multifunction Switch Circuit Malfunction.

2. Wiper switch in the OFF position, verify the scan tool Windshield Wiper Switch parameter is Off.

• If not the specified value, refer to Multifunction Switch Circuit Malfunction.




Circuit/System Testing


Rear Wiper Motor Circuit Malfunction
1. Ignition OFF, disconnect WPR relay.
2. Test for less than 20 ohms of resistance between the ground circuit terminal 85 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Test for less than 20 ohms of resistance between the ground circuit terminal 87A and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 87 and ground.

• If the test lamp does not illuminate, test or replace the underhood fuse block.

5. Install a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
6. Using the multifunction switch, command the low speed wipers ON and OFF. The test lamp should turn ON and OFF as commanded.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

7. Ignition OFF, disconnect the WPR HI relay.
8. Test for less than 2 ohms of resistance between the control circuit terminal 30 at the WPR relay and the control circuit terminal 30 at the WPR HI relay.

• If greater than the specified range, replace the underhood fuse block.

9. Connect the WPR relay.
10. Test for less than 20 ohms of resistance between the control circuit terminal 30 and ground.

• If greater than the specified range, test or replace the WPR relay.

11. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 85 and ground.

• If the test lamp does not illuminate, test or replace the underhood fuse block.

12. Install a test lamp between the control circuit terminal 30 and the ground circuit terminal 87.
13. Using the multifunction switch, command the low speed wipers ON. The test lamp should turn illuminate.

• If the test lamp does not illuminate, replace the WPR relay.

14. Install a test lamp between the B+ circuit terminal and the control circuit terminal 86.
15. Using the multifunction switch, command the high speed wipers ON and OFF. The test lamp should turn ON and OFF as commanded.

• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.


• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

16. Ignition OFF, connect the WPR HI replay. Disconnect the harness connector at the windshield wiper motor.
17. Test for less than 20 ohms of resistance between the ground circuit terminal 4 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

18. Connect a test lamp between the control circuit terminal 2 and ground.
19. Using the multifunction switch, command the low speed wipers ON and OFF. The test lamp should turn ON and OFF as commanded.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, test or replace the WPR HI relay.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the WPR HI relay.

20. Connect a test lamp between the control circuit terminal 1 and ground.
21. Using the multifunction switch, command the high speed wipers ON and OFF. The test lamp should turn ON and OFF as commanded.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, test or replace the WPR HI relay.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the WPR HI relay.

22. Verify a test lamp illuminates between the signal circuit terminal 3 and ground.

• If the test lamp does not illuminate, replace the BCM.

23. If all circuits test normal, test or replace the windshield wiper motor.



Component Testing

If any switch position is not within the specified range, replace the windshield wiper washer switch.



Rear Wiper Motor
1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
2. Install a 25A fused jumper wire between the control terminal 2 and 12 volts. Install a jumper wire between the ground terminal 4 and ground.
3. Verify the wiper motor is operating in the low speed mode.

• If the wiper motor is not in the low speed mode, replace the windshield wiper motor.

4. Install a 25A fused jumper wire between the control terminal 1 and 12 volts. Install a jumper wire between the ground terminal 4 and ground.
5. Verify the wiper motor is operating in the high speed mode.

• If the wiper motor is not in the high speed mode, replace the windshield wiper motor.




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure

* Windshield Wiper System Module Replacement (Windshield Wiper System Module Replacement)
* Steering Column Control Module Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for UEC replacement, setup, and programming


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