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 Windshield Washer Fluid Pump Control | 1 | 1 | 2 | --
Rear Windshield Washer Fluid Pump Ground | -- | 1 | -- | --
1. Washer Inoperative 2. Washers Always ON

### Circuit/System Description

The Underhood Electrical Center (UEC) controls the washer motor based on an input from the windshield washer switch which is part of the Steering Wheel Module (SWM). The UEC monitors the washer switch over the LSCAN data line. Both circuits at the washer pump are normally grounded at the UEC. When the front washers are commanded on the UEC applies B+ to circuit 228 and Circuit 392 remains grounded to activate a front windshield wash cycle. When a rear window wash cycle is requested the UEC applies B+ to Circuit 392 and ground to circuit 228 to command rear washers on.

### 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 scan tool information

### Circuit/System Verification

1. Ignition ON, wiper switch in the OFF position, observe the scan tool Rear Window Washer Status parameter while cycling the WASH switch ON and OFF. The parameter should cycle between OFF and ON.

⇒ | If the parameter does not cycle between the specified values, replace the wiper washer switch.

2. Operate the rear washers using the washer switch. Verify the washer pump activates and the low speed wipers turn on.

⇒ | If the washer pump does not activate, refer to Washer Pump Circuit Malfunction.

⇒ | If the low speed wipers do not turn on, refer to Windshield Wiper System Malfunction .

### Circuit/System Testing

#### Washer Pump Circuit Malfunction

1. Ignition OFF, disconnect the Underhood Electrical Center (UEC)
2. At connector X 1 connect a jumper wire between terminal 43 and ground.
3. At connector X 1 connect a fused jumper wire between terminal 42 and B+.
4. Verify the washer pump activates.

⇒ | If the rear washer pump does activate replace the UEC. refer to Control Module References for UEC replacement.

5. If the rear washer fluid pump does not activate, test the control circuit for an open/high resistance. If the fuse opens, test the control circuit for a short to ground.
6. If the washer pump still does not operate test for less then 3 ohms between terminal 42 and terminal 1 at washer pump connector.

⇒ | If greater than the specified ranges, test the ground circuit for an open/high resistance. If all values are with in specification and washer are inoperative refer to washer pump component testing.

### Component Testing

#### Washer Pump

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

⇒ | If the washer pump does not activate , replace the washer pump.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Washer Pump Replacement

• | Control Module References for UEC replacement, setup, and programming