B0283

DTC B0283

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provide 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 rear window defogger switch is activated, the HVAC control module energizes the rear defog relay by applying voltage to the rear defog relay control circuit. Ground for the relay coil is provided at G401. When the rear defog relay coil is energized, the switch contacts of the rear defog relay close allowing battery voltage to flow from the REAR DEFOG fuse through the closed switch contacts and out the relay switched output to the rear window defogger grid. Ground for the rear window defogger grid is provided at G402.


Conditions for Running the DTC

Battery voltage must be between 9-16 volts.


Conditions for Setting the DTC

C0283 02

This DTC will set when the BCM detects a short to ground in the rear defog relay control circuit for 1 second or greater.

C0283 05

This DTC will set when the BCM detects a short to voltage or an open/high resistance in the rear defog relay control circuit for 1 second or greater.


Action Taken When the DTC Sets

* The BCM stores the DTC to memory.
* The rear window defogger will not operate.



Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 100 malfunction-free ignition cycles have occurred.



Reference Information
Schematic Reference

Defogger Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Rear Window Defogger Description and Operation (Rear Window Defogger Description and Operation)


Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)


Circuit/System Testing

1. Ignition OFF, disconnect the rear window defog relay.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the relay coil ground circuit terminal R5 and ground.

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

3. Connect a test lamp between the rear defog relay control circuit terminal R1 and ground.
4. Command the rear window defog relay 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 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 HVAC control module.

5. If all circuits test normal, test or replace the rear window defog relay.



Repair Instructions

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

* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Liftgate Window Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for HVAC control module replacement, setup, and programming