GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2008 🢒 H2 🢒 Body Systems 🢒 Wipers and Washers 🢒 Washer Malfunction

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Windshield Washer Switch Signal

3

1

1

--

Rear Window Wiper/Washer Switch Signal

2

2

4

--

Windshield Washer Relay Control

3

1

1

--

Rear Window Washer Relay Control

2

2

4

--

Windshield Washer Pump Control

5

5

3

--

Rear Window Washer Pump Control

5

5

4

--

1. Windshield Washer Inoperative

2. Rear Window Washer Inoperative

3. Windshield Washer Always On

4. Rear Window Washer Always On

5. Windshield and Rear Window Washer Pump Inoperative

Circuit/System Description

The washer fluid pump is a reversible motor and is used to wash both the windshield and rear window.

When the windshield wash switch is pressed, ground is applied through the switch contacts and the windshield washer switch signal circuit to the body control module (BCM) indicating the windshield wash request. The BCM energizes the windshield wash relay by grounding the control circuit. With the windshield wash relay energized, battery voltage is supplied to the windshield wash control circuit of the washer fluid pump and grounded through the de-energized rear wash relay.

When the rear window wash switch is pressed, ignition voltage is applied through the switch contacts an the rear window wiper/washer switch signal circuit to the rear window wiper motor module. The rear window wiper motor module energizes the rear window wash relay by applying battery voltage to the relay control circuit. With the rear window wash relay energized, battery voltage is supplied to the rear window wash control circuit of the washer fluid pump and grounded through the de-energized windshield wash relay.

Reference Information

Schematic Reference

Wiper/Washer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Wiper/Washer System Description and Operation
    •  Rear Wiper/Washer System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, verify the rear wiper operates normally using the rear wiper switch.
    2. ⇒If the rear wiper does not operate properly, refer to Rear Wiper System Malfunction .
  2. Ignition ON, observe the scan tool Windshield Washer Switch parameter while pressing and releasing the windshield washer switch. The reading should change between Active and Inactive.
    3. ⇒If not the specified values refer to Windshield Washer Switch Circuit Test.
  3. Verify that a test lamp illuminates between the FRT WSW fuse and ground when the windshield wash switch is activated.
    4. ⇒If the test lamp does not illuminate, refer to Windshield Wash Relay Control Circuit Test.
  4. Verify that a test lamp illuminates between the REAR WSW fuse and ground when the rear window wash switch is activated.
    5. ⇒If the test lamp does not illuminate, refer to Rear Window Wash Relay Control Circuit Test.
  5. If the relay controls operate normal, refer to Washer Pump Control Circuit Test.

Circuit/System Testing

Windshield Washer Switch Circuit Test

  1. Ignition OFF, disconnect the X3 harness connector at the turn signal multifunction switch.
  2. Verify that a test lamp illuminates between B+ and the low reference circuit terminal M.
    3. ⇒If the test lamp does not illuminate, test the low reference circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Windshield Washer Switch parameter is Inactive.
    4. ⇒If not the specified value, test the signal circuit terminal L for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal L and the low reference circuit terminal M. Verify the scan tool Windshield Washer Switch parameter is Active.
    5. ⇒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.
  5. If all circuits test normal, test or replace the turn signal multifunction switch.

Windshield Wash Relay Control Circuit Test

  1. Verify that a test lamp illuminates between B+ and the FRT WSW and REAR WSW fuses.
    2. ⇒If the test lamp does not illuminate at both fuses replace the underhood fuse block.
  2. Disconnect the X4 harness connector at the BCM.
  3. Install a 3A fused jumper wire between the relay control circuit terminal 15 and ground. Verify that the windshield washer pump turns ON.
    4. ⇒If the windshield washer pump does not turn on, test the relay control circuit for an open/high resistance. If the circuit tests normal replace the underhood fuse block.
  4. If the circuits test normal replace the BCM.

Rear Window Wash Relay Control Circuit Test

  1. Verify that a test lamp illuminates between B+ and the FRT WSW and REAR WSW fuses.
    2. ⇒If the test lamp does not illuminate at both fuses replace the underhood fuse block.
  2. Disconnect the harness connector at the rear window wiper motor control module.
  3. Connect a test lamp between the switch signal circuit terminal E and ground.
  4. Ignition ON, press and release the rear window washer switch. The test lamp should turn ON and OFF when changing between the commanded states.
    5. ⇒If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear window wiper/washer switch.
    ⇒If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear window wiper/washer switch.
  5. Connect a 3A fused jumper wire between B+ and the relay control circuit terminal C. Verify that the rear window washer pump turns ON.
    6. ⇒If the rear window washer pump does not turn on, test the relay control circuit for an open/high resistance. If the circuit tests normal replace the underhood fuse block.
  6. If the circuits test normal replace the rear window wiper motor module.

Washer Pump Control Circuit Test

  1. Ignition OFF, disconnect the harness connector at the washer fluid pump.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the control circuit terminal 1 and ground.
    3. ⇒If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the underhood fuse block.
  3. Ignition OFF, test for less than 1.0 ohm of resistance between the control circuit terminal 2 and ground.
    4. ⇒If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the underhood fuse block.
  4. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
  5. Ignition ON, operate the windshield and rear window wash functions ON and OFF. The test lamp should turn ON when operating the windshield and rear window wash functions.
    6. ⇒If the test lamp remains OFF during either of the wash functions, test the affected control circuit for a short to ground. If the circuits test normal, replace the underhood fuse block.
  6. If all circuits test normal, test or replace the washer fluid pump.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Turn Signal Multifunction Switch Replacement
    •  Washer Pump Replacement
    •  Rear Window Wiper Control Module Replacement
    •  Control Module References for BCM replacement, programming, and setup