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.

### DTC Descriptor

DTC B370B 02: Rear Wiper Function Control Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Rear Wiper Switch Signal | 2 | 1 | 1 | --
Rear Window Wiper Control | 1 | 1 | 2 | --
Rear Window Wiper Relay Control | B370B 02 | 1 | 2 | --
Rear Window Wiper Ground | -- | 1 | 1 | --
1. Washer Inoperative 2. Washer Always ON

### Circuit/System Description

The body control module (BCM) controls the single speed rear wiper motor by its active high output to the external rear wiper motor relay. When the BCM activates its output and applies battery to the coil of the relay, the relay energizes, allowing battery voltage from the fuse to be applied through the switched contacts of the rear wiper motor relay to the control input of the rear wiper motor. The motor then operates continuously at low speed.

### Conditions for Running the DTC

• | Ignition ON.

• | The system voltage is between 9 V and 16 V.

### Conditions for Setting the DTC

A short to ground or an open/high resistance is detected in the rear window wiper control circuit.

### Action Taken When the DTC Sets

Rear wiper operation is suspended.

### Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

### 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 wiper by using the S78 Turn Signal/Multifunction Switch. Verify the M45 Rear Window Wiper Motor activates.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X2 at the X50D Fuse Block - Underhood.
2. Connect a test lamp between the control circuit terminal 11 X2 and ground.
3. Ignition ON, command the 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 X50D Fuse Block - Underhood.

### Component Testing

#### Relay Test

1. Ignition OFF, connect the harness connector X2 at the X50D Fuse Block - Underhood.
2. Disconnect the harness connector X4 at the K9 Body Control Module (BCM).
3. Test for 60-200 Ω between terminals 10 X4 and ground.

⇒ | If the resistance is not within the specified range, test the control circuit for a short to ground or an open/high resistance.

⇒ | If all circuits test normal, test or replace the X50D Fuse Block - Underhood.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for BCM replacement, setup, and programming.

• | Relay Replacement

• | LINK X, for UEC replacement.