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 Descriptors
DTC B0283 02: Electric Rear Defrost Circuit Short to GroundDTC B0283 05: Electric Rear Defrost Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
LED Backlighting Dimming Control | B2625 00 | 2 | 2 | -- |
Rear Defog Relay Control | B0283 02 | B0283 05 | B0283 05 | -- |
Rear Defog Relay Switch Control | 1 | 1 | 1 | -- |
Rear Defog Relay Switch B+ | 1 | 1 | -- | -- |
Rear Defog Relay Coil Ground | -- | B0283 05, 1 | -- | -- |
Rear Window Defogger Grid Ground | -- | 1 | -- | -- |
1. Rear Window Defogger Malfunction 2. Rear Window Defogger Indicator Malfunction | ||||
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 HVAC control module 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 HVAC control module 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 HVAC control module 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
Connector End View Reference
Window Systems Connector End Views
Description and Operation
Rear Window Defogger Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the rear window defog relay.
- Ignition OFF, test for less than 5.0 ohms of resistance between the relay coil ground circuit terminal R5 and ground.
- Connect a test lamp between the rear defog relay control circuit terminal R1 and ground.
- 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 all circuits test normal, test or replace the rear window 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, setup, and programming |
