Wash, Mist, Delay 1-5, Low, and Park are all low speed wiper motor functions controlled by the body control module (BCM). The BCM energizes the WPR 70 On/Off relay in order to operate the wiper motor at low speed. When energized, the output of the WPR 70 On/Off relay applies battery voltage through the WPR 52 high relay to the wiper motor.

The high speed wiper function operates independent of the wiper switch signal 1 circuit and any BCM output. During high speed wiper operation the windshield wiper switch high signal circuit directly energizes the WPR 70 high relay and also energizes the WPR 52 On/Off relay through the WIPER diode.

Schematic Reference

Wiper/Washer Schematics

Connector End View Reference

Wiper/Washer Connector End Views

Electrical Information Reference

Scan Tool Reference

BCM and Wiper Switch Verification

1. Ignition ON, observe the scan tool Windshield Wiper Switch parameter. The reading should display Off, Delay 1-5, Low/Mist/Hi while rotating the wiper switch through each delay and low speed positions.

⇒	If one or more of the wiper delay parameters are inoperative and the wiper low speed parameter functions, replace the windshield wiper switch.

⇒	If the low speed parameters are inoperative, perform the Windshield Wiper Switch Circuit/System Testing and/or the Windshield Wiper Switch Component Test.

2. Observe the scan tool 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, perform the Wipers do not Park Circuit/System Testing.

3. If all wiper position parameters displayed correctly on the scan tool, perform the Wiper Motor Circuit/System Testing.

BCM and Wiper Motor Verification

1. Command the Wiper Motor Relay On using a scan tool. The wipers should operate at low speed.

⇒	If the wipers do not work, perform the Wiper Motor Circuit/System Testing.

2. If all the wiper motor speeds function, perform the Windshield Wiper Switch Circuit/System Testing and/or the Windshield Wiper Switch Component Test.

Windshield Wiper Switch Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the windshield wiper switch.
2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground.

⇒	If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance.

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

⇒	If not Off, test the signal circuit terminal E for a short to voltage. If the circuit tests normal, replace the body control module.

4. Install a 3A fused jumper wire between the signal circuit terminal E and battery voltage. Verify the scan tool Windshield Wiper Switch parameter is Low/Mist/Hi.

⇒	If not Low/Mist/Hi, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the body control module.

5. Ignition Off, remove the WPR 52 high relay at the underhood fuse block.
6. Place the wiper switch in the high speed position.
7. Verify that a test lamp illuminates between the wiper switch high signal circuit terminal 86 and ground.

⇒	If the test lamp does not illuminate, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the windshield wiper/washer switch.

8. If all circuits test normal, test or replace the windshield wiper switch.

Wiper Motor Circuit/System Testing

1. Ignition OFF, remove the WPR 70 On/Off relay at the underhood fuse block.
2. Test for less than 5 ohms of resistance between the ground circuit terminal 85 and ground.

⇒	If greater than 5 ohms, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a lest lamp illuminates between the B+ terminal 87 and ground.

⇒	If the test lamp does not illuminate, test the WPR Fuse 59 for an open. If the fuse tests normal, replace the underhood fuse block.

4. Connect a test lamp between the relay control circuit terminal 86 and ground.
5. Activate the wiper MIST switch ON and OFF. 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 body control module.

⇒	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 body control module.

6. Ignition OFF, install the WPR 70 On/Off relay.
7. Remove the WPR 52 high relay at the underhood fuse block.
8. Ignition OFF, test for less that 5 ohms of resistance between the wiper relay ground circuit terminal 85 and ground.

⇒	If greater than 5 ohms, test the ground circuit for an open/high resistance.

9. Connect a test lamp between the control circuit terminal 30 and ground.
10. Ignition ON, activate the wiper MIST switch ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp does not illuminate, replace the WPR 70 On/Off relay.

11. Place the wiper switch in the HIGH speed position. Verify that a test lamp illuminates between the wiper switch high signal circuit terminal 86 and ground.

⇒	If the test lamp does not illuminate, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the windshield wiper/washer switch.

12. Ignition OFF, install the WPR 52 high relay.
13. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
14. Test for less than 5 ohms of resistance between the ground circuit terminal 1 and ground.

⇒	If greater than 5 ohms, test the ground circuit for an open/high resistance.

15. Ignition ON, place the switch in the LOW speed position. Verify that a test lamp illuminates between the low speed control circuit terminal 5 and ground.

⇒	If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the WPR 52 high relay.

16. Place the switch in the HIGH speed position. Verify that a test lamp illuminates between the high speed control circuit terminal 4 and ground.

⇒	If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the WPR 52 high relay.

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

Wipers Do Not Park Circuit/System Testing

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 Inactive, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, test or replace the body control module.

3. Install a 3A fused jumper wire between the wiper motor park switch signal circuit terminal 2 and ground. Verify the scan tool Wiper Park Switch parameter is Active.

⇒	If not Active, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the body control module.

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

Windshield Wiper/Washer Switch

1. With the ignition OFF, disconnect the harness connector at the windshield wiper/washer switch.
2. Test the resistance between terminals D and E. Rotate the wiper switch and compare the resistance readings to the values in the Windshield Wiper Switch Values table below for MIST, each DELAY and LOW speed.

⇒	If the resistance is not within the specified range, replace the windshield wiper/washer switch.

3. Test for infinite resistance with the wiper switch in the High speed position.

⇒	If less than infinite ohms, replace the windshield wiper/washer switch.

4. Test for infinite resistance between terminals D and C while rotating the wiper switch to MIST, each DELAY and LOW speed positions.

⇒	If the less than infinite, replace the windshield wiper/washer switch.

5. Test for less than 5 ohms of resistance with the wiper switch in the High speed position.

⇒	If greater than 5 ohm, replace the windshield wiper/washer switch.

6. Test for infinite resistance between terminals D and B while rotating the wiper switch to MIST, each DELAY and LOW speed positions.

⇒	If less than infinite, replace the windshield wiper/washer switch.

7. Test for less than 5 ohm of resistance while pressing the WASHER switch.

⇒	If greater than 5 ohm, replace the windshield wiper/washer switch.

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

Relay Test

1. Ignition OFF, remove the relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than infinite, replace the relay.

4. Test for less than 2 ohms of resistance between terminal 30 and 87A.

⇒	If greater than 2 ohms, replace the relay.

5. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.

⇒	If greater than 2 ohms, replace the relay.

Windshield Wiper Motor Dynamic Test

1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
2. Install a 25A fused jumper wire between the control terminal D and 12 volts. Install a jumper wire between the ground terminal A 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 25A fused jumper wire between the control terminal C and 12 volts. Install a jumper wire between the ground terminal A 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.