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 Washer Switch Control | 2 | 1 | 1 | --
Rear Washer Relay Control | B3811 02 | 1 | 2 | --
Rear Washer Fluid Pump Control | 1 | 1 | 2 | --
Rear Washer Fluid Pump Ground | -- | 1 | 1, 2 | --
1. Rear Washer Inoperative 2. Rear Washer Always ON

### Circuit/System Description

When the Body Control Module detects that the Rear wiper/wash switch has activated the momentary Wash switch, it activates a High Side Drive output which supplies Battery to the coil of the Rear Washer Pump Relay. This energizes the Relay, which switches Battery Power to the Washer Pump Motor. The BCM will also activate continuous Low Speed Windshield Wipers as described above. This Washer and Wiper operation shall be continued so long as the switch remains active. Upon termination the Rear Wash Motor will be deactivated and the Wiper shall move to its Park Position and deactivate.

### Reference Information

#### 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for diagnostic tester information

### Circuit/System Verification

Operate the rear washers by using the S78 Turn Signal/Multifunction Switch. Verify the G24 Windshield Washer Fluid Pump activates.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X2 at the X50A Fuse Block - Underhood Primary.
2. Connect a test lamp between the control circuit terminal X2 59 and ground.
3. Ignition ON, command the rear washer ON and OFF using the S78 Turn Signal/Multifunction Switch. 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 K9 Body Control Module (BCM).

⇒ | 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 K9 Body Control Module (BCM).

4. If all circuits test normal, test or replace the X50A Fuse Block - Underhood Primary.

### Component Testing

#### Output Control Tests

1. Ignition ON, command the Rear Washer ON and OFF with a scan tool. Observe the KR6 Rear Window Washer Pump Relay clicks and the G24 Windshield Washer Fluid Pump runs.

⇒ | If the KR6 Rear Window Washer Pump Relay does not work, replace the X50A Fuse Block - Underhood Primary.

#### Multifunction Switch

#### Static Test

1. Ignition OFF, disconnect the harness connector X3 at the K9 Body Control Module (BCM).
2. Test for less than 5 Ω between ground terminal X3 10 and signal circuit terminal X3 25 while activating the rear wash switch.

⇒ | If the resistance is not within the specified range, test for an open/high resistance.

3. Test for greater than 500 kΩ between ground terminal X3 10 and signal circuit terminal X3 25 with not activated rear wash switch.

⇒ | If the resistance is not within the specified range, test for a short to ground.

4. If all circuits test normal, replace the S78 Turn Signal/Multifunction Switch.

#### Washer Pump

#### Dynamic Test

1. Ignition OFF, disconnect the harness connector at the G24 Windshield Washer Fluid Pump.
2. Install a 10 A fused jumper wire between the control terminal 2 and 12 volts. Install a jumper wire between the ground terminal 1 and ground.
3. Verify the G24 Windshield washer fluid pump is activated.

⇒ | If the G24 Windshield Washer Fluid Pump does not activate , replace the G24 Windshield Washer Fluid Pump.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming

Relay Replacement

Windshield Washer Pump Replacement

Windshield Wiper and Washer Switch Replacement

LInk X for UEC replacement.