B0283

DTC B0283

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC B0283 02
- Electric Rear Defrost Circuit Short To Ground

DTC B0283 05
- Electric Rear Defrost Circuit Short To Battery or Open

Diagnostic Fault Information





Circuit/System Description

When the HVAC control module receives a rear window defog request from the radio/HVAC control, the HVAC control module will supply voltage to the relay coil. Battery positive voltage is supplied at all times to the relay switched input and the relay coil is always grounded. This allows current from the relay switched input to flow through the switch contacts and out the relay switched output to the rear window defogger grid.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

B0283 02

The HVAC control module detects a short to ground in the relay control circuit.

B0283 05

The HVAC control module detects a short to voltage or an open/high resistance in the rear window defogger relay control circuit or an open/high resistance in the rear window defogger relay ground circuit.

Action Taken When the DTC Sets

* If B0283 02 is current, the rear window defogger grid will operate continuously.
* If B0283 05 is current, the rear window defogger grid will be inoperative.

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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Rear Window Defogger Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Engine running, command the Rear Defog ON and OFF with a scan tool, the rear window defogger grid should turn ON or OFF while changing between the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the K55 DEFOG RR relay.
2. Test for less than 5 ohm between the ground circuit terminal 86 and ground.

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

3. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
4. Engine running, command the Rear Defog 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 K33 HVAC control module.
• 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 K33 HVAC control module.

5. If all circuits test normal, test or replace the K55 DEFOG RR relay.

Component Testing

Relay Test
1. Ignition OFF, disconnect the K55 DEFOG RR relay.
2. Test for 60-180 ohms between terminals 85 and 86.

• If not within the specified range, replace the K55 DEFOG RR relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87

• If not the specified value, replace the K55 DEFOG RR relay.

4. Install a 25A fused jumper wire between relay terminal 86 and 12V. Install a jumper wire between relay terminal 85 and ground. Test for less than 2 ohms between terminals 30 and 87.

• If greater than the specified range, replace the K55 DEFOG RR relay.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Relay Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for the HVAC control module replacement, setup and programming