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Home >> Hummer >> 2008 >> H2 V8-6.2L >> Repair and Diagnosis >> Wiper and Washer Systems >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Windshield Wiper System Malfunction

Windshield Wiper System Malfunction



Windshield Wiper System Malfunction

Diagnostic Instructions

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



Diagnostic Fault Information






Circuit/System Description

Wiper Mist, Delay 1-5, and Low are all low speed wiper motor functions that are controlled by the body control module (BCM). When the wiper switch is placed in one of the LOW speed wiper modes, ground is applied through the switch contacts a series of internal resistors and the wiper switch low signal circuit to the BCM. In response to this signal, the BCM energizes the WIPER CONTROL relay by applying battery voltage through the wiper relay control circuit to the coil side of the relay. This allows battery positive voltage from the WPR fuse to flow through the switch input side of the WIPER CONTROL relay and out to the switch input side of the WIPER SPEED relay. Since the wiper high relay is de-energized and its switch contacts are normally closed to the low speed control circuit of the windshield wiper motor, the motor will operate at low speed.


When the wiper switch is placed in the HIGH speed position, ground is applied through the switch contacts and the wiper switch high signal circuit to the BCM indicating the wiper high speed request. The BCM then energizes WIPER CONTROL relay as stated above and the WIPER SPEED relay by applying ground through the control circuit to the coil side of the relay. With the WIPER SPEED relay energized and its switch contacts closed to the high speed control circuit of the wiper motor, the motor will operate at high speed.


Diagnostic Aids

* A short to ground in the following circuits will open the WPR fuse:

- Ignition 1 voltage
- Windshield wiper motor relay coil supply voltage
- Windshield wiper switch high signal
- Windshield wiper motor low speed control
- Windshield wiper motor high speed control

* A short to B+ on any of the wiper/washer switch signal circuits will open the ground trace in the wiper switch.



Reference Information
Schematic Reference

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

Component Connector End Views (Component Connector End 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

Programming and Relearning (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Ignition ON, observe the scan tool BCM Windshield Wiper Switch parameter. The reading should display Off, Intermittent, Low and High while rotating the wiper switch.

• If one or more of the wiper delay functions are inoperative and the wiper low speed parameter functions, replace the turn signal/multifunction switch.
• If the low speed and/or high speed parameters are inoperative, refer to the Multifunction Switch Circuit Test and/or the 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 the Wipers do not Park Circuit Test.

3. Disconnect the windshield wiper motor connector.
4. Connect a test lamp between the TP 1 terminal in the underhood fuse block and ground.
5. Ignition ON, 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 the WIPER CONTROL Relay Control Circuit Test.

6. Connect a test lamp between the TP 2 terminal in the underhood fuse block and ground.
7. Ignition ON, verify the test lamp turns on and off while turning the windshield wiper switch between HIGH and OFF.

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

8. If the low or high speed wipers are inoperative, refer to the Wiper Motor Circuit Test and/or the Wiper Motor Component Test.



Circuit/System Testing


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 of resistance 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 A for a short to ground. If the circuit tests normal, replace the BCM.

3. Install a 3-amp fused jumper wire between the wiper motor park switch signal circuit terminal A 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 WIPER CONTROL 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 the WIPER CONTROL relay control circuit terminal 20 and B+. 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 the WIPER CONTROL relay control circuit terminal 20 and B+.
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 low 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 of resistance between the wiper motor ground circuit terminal B 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 C 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 D 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.



Component Testing


Multifunction Switch
1. Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
2. Test the resistance between terminals M and N. 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 turn signal/multifunction switch.

3. Test for infinite resistance between terminals M and K while rotating the wiper switch to MIST, each DELAY and LOW speed positions.

• If the less than infinite, replace the turn signal/multifunction switch.

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

• If greater than 5 ohm, replace the turn signal/multifunction switch.

5. Test for infinite resistance between terminals M and L while rotating the wiper switch to MIST, each DELAY and LOW speed positions.

• If less than infinite, replace the turn signal/multifunction switch.

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

• If greater than 5 ohm, replace the turn signal/multifunction 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 voltage before replacing the switch.








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 the control terminal 1 and 12 volts. Install a jumper wire between the ground 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 the control terminal 4 and 12 volts. Install a jumper wire between the ground 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.




Repair Instructions

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

* Turn Signal Multifunction Switch Replacement (Turn Signal Multifunction Switch Replacement)
* Windshield Wiper Motor Cover Replacement - Front (Windshield Wiper Motor Cover Replacement - Front)
* Underhood Electrical Center or Junction Block Replacement (Underhood Electrical Center or Junction Block Replacement)
* Programming and Relearning (Programming and Relearning) for BCM replacement, setup, and programming


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