The body control module (BCM) controls the wiper motor based on input from the windshield wiper washer switch. The BCM monitors the wiper washer switch through three separate signal circuits and a ground circuit. The windshield wiper switch high signal circuit is used to determine high speed wiper operation, the windshield wiper switch low signal is used to determine low speed, intermittent, and mist operation through the use of a resistor ladder, and windshield washer switch signal circuit is used to determine washer operation.

The BCM controls the windshield wiper motor through two output controls, controlling two relays which determine the desired wiper speed, high or low.

Schematic Reference

Wiper/Washer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Wiper/Washer System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, wiper switch OFF, verify the scan tool Windshield Washer Switch parameter is Inactive.
2. Wiper switch OFF, verify the scan tool Windshield Wiper Switch parameter is Off.
3. Wiper switch OFF, verify the scan tool Wiper High Speed Switch parameter is Inactive.
4. Wiper switch in the LOW position, verify the scan tool Windshield Wiper Switch parameter is Low.
5. Wiper switch in the HIGH position, verify the scan tool Wiper High Speed Switch parameter is Active.
6. Wiper switch in the INT position, verify the scan tool Windshield Wiper Switch parameter is Intermittent.
7. Wiper switch in the INT position, observe the scan tool Wiper Delay Setting parameter while cycling the delay adjustment switch from long delay to short delay. The parameter should cycle between D1 and D5 as each delay position is selected.
8. Wiper switch in the LOW position, verify the windshield wipers are cycling at low speed.
9. Wiper switch in the HIGH position, verify the windshield wipers are cycling at high speed.
10. Wiper switch in the INT position, cycling the delay adjustment switch from long delay to short delay. Verify the wiper delay time decreases from long delay to short delay as each delay position is selected.

Windshield Wiper Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the Windshield Wiper/Washer Switch.
2. Test for less than 40 Ω between the low reference circuit terminal 8 and ground.

⇒	If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the BCM.

3. Ignition ON, verify the scan tool Windshield Wiper Switch parameter is Off.

⇒	If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the BCM.

4. Verify the scan tool Wiper High Speed Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the BCM.

5. Install a 3A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool Windshield Wiper Switch parameter is Switch Fault.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

6. Install a 3A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Wiper High Speed Switch parameter is Active.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

7. If all circuits test normal, test or replace the Windshield Wiper/Washer Switch.

Windshield Wiper Motor Malfunction

1. Ignition OFF, disconnect WIPER LO relay.
2. Ignition OFF, wait 20 seconds, Test for less than 1Ω between the ground circuit terminal 85 and ground.

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

3. Ignition OFF, wait 20 seconds, test for less than 1Ω 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 that a test lamp illuminates between the B+ circuit terminal 87 and ground.

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

5. Ignition OFF, wait 20 seconds, connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
6. Ignition ON, command the WIPER LO relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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 WIPER HIGH relay.
8. Test for less than 1 Ω between the control circuit terminal 30 at the WIPER LO relay and the control circuit terminal 30 at the WIPER HIGH relay.

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

9. Connect the WIPER LO relay.
10. Ignition OFF, wiper switch OFF, wait 20 seconds, Test for less than 1 Ω between the control circuit terminal  30 and ground.

⇒	If greater than the specified range, test or replace the WIPER LO relay.

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

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

12. Ignition OFF, connect a test lamp between the control circuit terminal 30 and ground.
13. Command the WIPER LO relay ON and OFF with a scan tool. The test lamp should turn illuminate.

⇒	If the test lamp does not illuminate, replace the WIPER LO relay.

14. Ignition OFF, remove WIPER HIGH relay, connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
15. Command the Wiper High relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between commanded states.

⇒	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 WIPER HIGH relay. Disconnect the harness connector at the windshield wiper motor.
17. Test for less than 5Ω between the ground circuit terminal 3 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 1 and ground.
19. Ignition ON, command the WIPER LO relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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 WIPER HIGH 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 WIPER HIGH relay.

20. Ignition OFF, connect a test lamp between the control circuit terminal 2 and ground.
21. Lo wipers ON, command the Wiper High speed relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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 WIPER HIGH 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 WIPER HIGH relay.

22. Wipers OFF, test for B+ between the signal circuit terminal 4 and ground.

⇒	If not the specified value, test the signal circuit for a short to ground or an open high resistance. If the circuit tests normal, replace the BCM.

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

Windshield Wiper/Washer Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the Windshield Wiper/Washer Switch.
2. With the wiper switch in the HIGH position, test for less than 2 ohms between the low reference terminal 8 and the signal terminal 4.

⇒	If greater than the specified range, replace the Windshield Wiper/Washer Switch.

Important: If the switch tests open in any switch position other than Off, test the signal circuits for a short to voltage before replacing the switch.

3. While cycling the wiper switch through each delay and speed position, test for the specified resistance between the low reference terminal 8 and the signal terminal 7.

Windshield Wiper Motor

1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
2. Install a 25 A fused jumper wire between B+ and the control terminal 1. Install a jumper wire between the terminal 3 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 25 A fused jumper wire between B+ and the control terminal 2. Install a jumper wire between the terminal 3 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.