For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Rear Window Wiper Motor B+ | 1 | 1 | -- | --
Rear Window Wiper Motor Ignition Voltage | 1 | 1 | -- | --
Rear Window Wiper/Washer Switch Ignition Voltage | 1 | 1 | -- | --
Rear Window Wiper Switch Signal | 1 | 1 | 2 | --
Rear Window Wiper Motor Ground | -- | 1 | -- | --
1. Rear Window Wiper Motor Inoperative 2. Rear Window Wiper Motor Always On

### Circuit/System Description

#### WDA/Z88

The rear wiper is controlled based on an input from the rear wiper/washer portion of the multifunction switch. When closed, the wiper ON and wiper DELAY switches provide a unique voltage signal to the rear window wiper motor indicating the desired speed. Each switch has a unique resistor that drops the voltage to a specified value which is interpreted by the rear window wiper motor as ON or DELAY. The rear wiper motor receives B+ voltage from the I/P fuse block and accessory voltage from the body control module (BCM).

#### W49

The rear wiper is controlled based on an input from the rear wiper/washer switch. When closed, the wiper ON switch provides a voltage signal to the rear window wiper motor indicating rear wiper operation is requested. The rear wiper motor receives B+ voltage from the I/P fuse block and accessory voltage from the body control module (BCM).

### Reference Information

#### Schematic Reference

Wiper/Washer Schematics

#### Connector End View Reference

Component Connector End Views

#### 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

Command the rear wiper ON using the rear wiper switch. The rear wiper should activate.

### Circuit/System Testing

#### WDA/Z88

1. Ignition OFF, disconnect the harness connector X1 at the multifunction switch.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 4 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, refer to Power Mode Mismatch.

3. Ignition OFF, connect the harness connector at the multifunction switch. Disconnect the harness connector at the rear window wiper motor.
4. Test for less than 20 ohms between the ground circuit terminal B and ground.

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

5. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal A and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

6. Verify a test lamp illuminates between the ignition circuit terminal E and ground.

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

7. Rear wiper switch in the ON position, test for B+ between the signal circuit terminal D and ground.

⇒ | If less than the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, test or replace the multifunction switch.

8. Rear wiper switch in the DELAY position, test for B+ between the signal circuit terminal D and ground.

⇒ | If less than the specified value, test or replace the multifunction switch.

9. If all circuits test normal, test or replace the rear window wiper motor.

#### W49

1. Ignition OFF, disconnect the harness connector at the rear wiper switch.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 6 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, refer to Power Mode Mismatch.

3. Ignition OFF, connect the harness connector at the rear wiper switch. Disconnect the harness connector at the rear window wiper motor.
4. Test for less than 20 ohms between the ground circuit terminal B and ground.

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

5. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal A and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

6. Verify a test lamp illuminates between the ignition circuit terminal E and ground.

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

7. Rear wiper switch in the ON position, verify a test lamp illuminates between the signal circuit terminal D and ground.

⇒ | If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the I/P switch assembly.

8. If all circuits test normal, test or replace the rear window wiper motor.

### Component Testing

#### Multifunction Switch (WDA/Z88)

1. Ignition OFF, disconnect the X1 harness connector multifunction switch.
2. Rear wiper switch in the OFF position, test for infinite resistance between the ignition terminal 4 and the signal terminal 5.

⇒ | If not the specified value, replace the multifunction switch.

3. Rear wiper switch in the ON position, test for 2000-2400 ohms between the ignition terminal 4 and the signal terminal 5.

⇒ | If not within the specified range, replace the multifunction switch.

4. Rear wiper switch in the DELAY position, test for 650-800 ohms between the ignition terminal 4 and the signal terminal 5.

⇒ | If not within the specified range, replace the multifunction switch.

#### I/P Switch Assembly (W49)

1. Ignition OFF, disconnect the harness I/P switch assembly.
2. Rear wiper switch in the OFF position, test for infinite resistance between the ignition terminal 6 and the signal terminal 5.

⇒ | If not the specified value, replace the I/P switch assembly.

3. Rear wiper switch in the ON position, test for less than 5 ohms between the ignition terminal 6 and the signal terminal 5.

⇒ | If not within the specified range, replace the I/P switch assembly.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Turn Signal Multifunction Switch Replacement

• | Rear Window Wiper Motor Replacement