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 windshield wiper motor park operation is controlled by the BCM. The BCM recieves an input from the park switch to determine wiper blade position. When the wiper blades are at the bottom of the windshield glass in park position the wiper park switch will open and the circuit will be pulled up to B+ by the BCM. The park signal will be pulled to ground by the wiper motor park switch while the wiper blades are not in the park position.

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 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.

3. Wiper switch in the OFF position, verify the scan tool Wiper Motor Relay Status parameter is OFF.

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

4. Wiper switch in the LO position, verify the scan tool Windshield Wiper Switch parameter is Low/Mist/High.

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

5. Wiper switch in the HIGH position, verify the scan tool Wiper High Speed Switch parameter is Low/Mist/High.

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

6. 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.

⇒	If not the specified value, test or replace the Multifunction Switch.

7. Wiper switch in the LO position, verify the windshield wipers are cycling at the low speed.

⇒	If the wipers are not operating at the low speed, refer to Windshield Wiper Motor Circuit Malfunction.

8. Wiper switch in the HIGH position, verify the windshield wipers are cycling at the high speed.

⇒	If the wipers are not operating at the low speed, refer to Windshield Wiper Motor Circuit Malfunction.

9. 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.

⇒	If the delay does not change as specified, refer to Windshield Wiper Motor Circuit Malfunction.

Multifunction Switch Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the windshield wiper washer multifunction switch.
2. Ignition ON, test for B+ at the windshield wiper washer multifunction switch Accessory Voltage circuit terminal D

⇒	If not the specified value, test the Accessory Voltage circuit for a short to ground 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 Windshield Wiper Switch Signal 1 circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the Windshield Wiper Switch Signal 1 circuit terminal E and B+. Verify the scan tool Windshield Wiper Switch parameter is Low/Mist/High.

⇒	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.

5. Install a 3A fused jumper wire between the Windshield Wiper Switch Signal 2 circuit terminal C and ground. Verify the scan tool Windshield Wiper Switch parameter Low/Mist/High.

⇒	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. If all circuits test normal, test or replace the Multifunction Switch.

Windshield Wiper Motor Circuit Malfunction

1. Ignition OFF, disconnect Wiper 1 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 WIPER 2 relay.
8. Test for less than 2 ohms of resistance between the control circuit terminal 30 at the WIPER 2 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 1 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 WIPER 1 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 WIPER 2 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 WIPER 2 Relay. Disconnect the harness connector at the windshield wiper motor.
17. Test for less than 20 ohms of resistance between the ground circuit terminal C 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 E 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 WIPER 2 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  2 Relay.

20. Connect a test lamp between the control circuit terminal D 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 WIPER  2 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  2 Relay.

22. Verify a test lamp illuminates between the signal circuit terminal B 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.

Multifunction Switch

1. Disconnect the windshield wiper washer switch harness connector at the multifunction switch.
2. With the wiper switch in the HIGH position, test for less than 2 ohms of resistance between the Windshield Wiper Switch Signal 1 terminal E and the Windshield Wiper Switch Signal 2 terminal C.

⇒	If greater than the specified range, replace the windshield wiper washer switch.

3. While cycling the wiper switch through each delay and speed position, test for the specified resistance between the Accessory Voltage terminal D and the signal 1 terminal E.

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.

Windshield 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 E and 12 volts. Install a jumper wire between the ground terminal C 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 D and 12 volts. Install a jumper wire between the ground terminal C 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