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. Observe the scan tool Windshield Wiper Switch parameter while rotating the wiper switch. The reading should change between Off, Intermittent, Low, and High.

⇒	If the Windshield Wiper Switch parameter is incorrect in the Low or High switch positions, refer to the Multifunction Switch Circuit Test and/or the Turn Signal Multifunction Switch Component Test.

2. Observe the scan tool BCM Wiper Park Switch parameter. The reading should display Active when the wipers are parked and Inactive with the wipers ON or out of the park position.

⇒	If the Wiper Park Switch parameter is always Active or Inactive, refer to Wipers do not Park Circuit Test.

3. Connect a test lamp between the TP 1 terminal in the underhood fuse block and ground.
4. Verify the test lamp turns on and off while turning the windshield wiper switch between LOW and OFF.

⇒	If the test lamp does not turn on and off while changing between the commanded states, refer to Wiper Control Relay Control Circuit Test.

5. Ignition ON, operate the windshield wiper switch through the Delay, Low, and High positions.

⇒	If the windshield wipers are inoperative in 1 or more of the delay settings only, test or replace the turn signal multifunction switch.

⇒	If the windshield wipers operate at high speed while the switch is in the Low position, refer to Wiper Speed Relay Control Circuit Test.

⇒	If the windshield wipers operate at low speed while the switch is in the High position, refer to Wiper Speed Relay Control Circuit Test.

⇒	If the windshield wipers are inoperative in the Low or High switch positions, refer to Wiper Motor Circuit Test and/or the Wiper Motor Component Test.

Multifunction Switch Circuit Test

1. Ignition OFF, disconnect the X3 harness connector at the turn signal multifunction switch.
2. Ignition OFF, test for less than 20 ohms between the low reference circuit terminal M and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

3. Verify the scan tool Windshield Wiper Switch parameter is Off.

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

5. Install a 3-amp fused jumper wire between the signal circuit terminal N 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 3-amp fused jumper wire between the signal circuit terminal K 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, replace the turn signal multifunction switch.

Wipers Do Not Park Circuit Test

1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
2. Ignition ON, verify the scan tool BCM Wiper Park Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.

3. Install a 3-amp fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Wiper Park Switch parameter is Active.

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

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

Wiper Control Relay Control Circuit Test

1. Ignition OFF, disconnect the X5 harness connector at the BCM.
2. Ignition ON, verify that the low speed wipers are not on.

⇒	If the low speed wipers are on, test the relay control circuit terminal 20 for a short to voltage. If the circuit tests normal, replace the underhood fuse block.

3. Install a 10A fused jumper wire between B+ and the relay control circuit terminal 20. Verify the low speed wipers are on.

⇒	If the low speed wipers are not on, test the relay control circuit for an open/high resistance or short to ground. If the circuit tests normal replace the underhood fuse block.

4. If all circuits test normal, replace the BCM.

Wiper Speed Relay Control Circuit Test

1. Ignition OFF, disconnect the X5 harness connector at the BCM.
2. Install a 10A fused jumper wire between B+ and the WIPER CONTROL relay control circuit terminal 20.
3. Ignition ON, verify that the high speed wipers are not on.

⇒	If the high speed wipers are on, test the WIPER SPEED relay control circuit terminal 21 for a short to ground. If the circuit tests normal, replace the underhood fuse block.

4. Install a 10A fused jumper wire between the WIPER SPEED relay control circuit terminal 21 and ground. Verify the high speed wipers are on.

⇒	If the high speed wipers are not on, test the relay control circuit for an open/high resistance or short to voltage. If the circuit tests normal replace the underhood fuse block.

5. If all circuits test normal, replace the BCM.

Wiper Motor Circuit Test

1. Disconnect the harness connector at the windshield wiper motor.
2. Test for less that 1 ohm between the wiper motor ground circuit terminal 5 and ground.

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

3. Connect a test lamp between the low speed motor control circuit terminal 1 and ground.
4. Ignition ON, command the Wiper 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 underhood fuse block.

⇒	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 underhood fuse block.

5. Connect a test lamp between the high speed motor control circuit terminal 4 and ground.
6. Wiper switch in the LOW position, 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, replace the underhood fuse block.

⇒	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 underhood fuse block.

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

Turn Signal Multifunction Switch

1. Ignition OFF, disconnect the X1 harness connector at the turn signal multifunction switch.
2. With the wiper switch in the HIGH position, test for less than 2 ohms between the low reference terminal M and the signal terminal K.

⇒	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 M and the signal terminal N.

Windshield Wiper Motor Dynamic Test

1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
2. Install a 25-amp fused jumper wire between B+ and the control terminal 1. Install a jumper wire between the terminal 5 and ground.
3. The wiper motor should be in low speed mode.

⇒	If the wiper motor is not in the low speed mode replace the motor.

4. Install a 25-amp fused jumper wire between B+ and the control terminal 4. Install a jumper wire between the terminal 5 and ground.
5. The wiper motor should be in the high speed mode.

⇒	If the wiper motor is not in the high speed mode replace the motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.