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 B0283 00: Rear Window Heating Circuit Malfunction

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
K2 Relay B+ | 2 | 2 | -- | --
Rear Defrost Switch Signal | B3743 5A | 2 | 2 | --
Rear Defog Relay Control | B0283 00 | B0283 00 | B0283 00 | --
Rear Defog Indicator Control | B0969 02 | 3 | B0969 01 | --
Rear Window Defogger Grid Control | 2 | 2 | 1 | --
Rear Window Defogger Grid Ground | -- | 2 | 2 | --
1. Rear Defogger Always On 2. Rear Defogger Inoperative 3. Rear Defogger Indicator Inoperative

### Circuit/System Description

The rear fuse block monitors the voltage level on the supply voltage circuit of the K2 relay. The voltage level should be low while the K2 relay is de-energized. The voltage will be near system voltage when the rear fuse block energizes the K2 relay.

### Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

### Conditions for Setting the DTC

When the rear fuse block detects a fault in the relay control circuit for 1 second or greater.

### Action Taken When the DTC Sets

The rear window defogger will not operate.

### Conditions for Clearing the DTC

• | The DTC will be current for as long as the fault is present.

• | When the fault is no longer present, the DTC will be a history DTC.

• | A history DTC will clear after 50 ignition cycles.

### Reference Information

#### Schematic Reference

Defogger Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Rear Window Defogger 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

Ignition ON, command the REC Heated Rear Window Test ON and OFF with a scan tool. The rear window defogger should turn ON and OFF when changing between the commanded states.

### Circuit/System Testing

1. Ignition OFF, disconnect the K2 relay.
2. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
3. Ignition ON, command the REC Heated Rear Window Test ON and OFF with a scan tool. 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 rear fuse block.

⇒ | 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 rear fuse block.

4. If all circuits test normal, test or replace the K2 relay.

### Component Testing

1. Ignition OFF, disconnect the K2 relay.
2. Test for 60-180 ohms between terminals 85 and 86.

⇒ | If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If greater than the specified range, replace the relay.

4. Install a 40A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

⇒ | If greater than the specified range, replace the relay

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module References for rear fuse block replacement, setup, and programming