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 06: Electric Rear Defrost Circuit Short to Ground or OpenDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Rear Defogger Battery Supply | 1 | 1 | -- | -- |
Rear Defogger Relay Control | B0283 06 | B0283 06 | 2 | -- |
Rear Defogger Element Supply | 1 | 1 | 2 | -- |
Rear Defogger Relay Coil Ground | -- | B0283 06 | -- | -- |
Rear Defogger Element Ground | -- | 1 | -- | -- |
1. Rear Defogger Inoperative 2. Rear Defogger Always ON | ||||
Circuit/System Description
The HVAC control module controls the rear window defroster through the REAR DEFOG relay located in the underhood fuse block. When the rear defroster is activated the HVAC control module supplies battery voltage through the defroster relay control circuit to energize the relay coil.
Conditions for Running the DTC
| • | Battery voltage is within 8.7-16.5 volts. |
| • | The ignition is ON. |
Conditions for Setting the DTC
The defroster relay control circuit is open or shorted to ground.
Action Taken When the DTC Sets
The defroster relay control will be deactivated.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a fault. |
| • | The history DTC will clear after 50 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Window Systems Connector End Views
Electrical Information Reference
DTC Type Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, remove the REAR DEFOG relay in the underhood fuse block.
- Test for less than 1 ohm of resistance between the relay coil ground circuit terminal 85 and ground.
- Connect a test lamp between the relay coil control circuit terminal 86 and the ground circuit terminal 85.
- Ignition ON, operate the rear window defroster ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, replace the REAR DEFOG relay.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for HVAC control module replacement, programming, and setup
