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: Electric Rear Defrost CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Rear Defog Relay B+ | 2 | 2 | -- | -- |
Rear Defog Relay Control | B0283 | B0283 | B0283 | -- |
Rear Window Defogger Grid Control | 2 | 2 | 1 | -- |
HVAC Serial Data | 2 | 2 | 2 | -- |
Rear Window Defogger Grid Ground | -- | 2 | 2 | -- |
1. Rear defogger always ON 2. Rear defogger inoperative | ||||
Circuit/System Description
The body control module (BCM) monitors the voltage level on the supply voltage circuit of the R/DEFOG relay. The voltage level should be low while the R/DEFOG relay is de-energized. The voltage will be near system voltage when the BCM energizes the R/DEFOG relay.
Conditions for Running the DTC
Battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
The BCM detects a fault in the rear defog relay control circuit for 1 second or greater.
Action Taken When the DTC Sets
The rear window defogger will malfunction.
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
Connector End View Reference
Description and Operation
Rear Window Defogger Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, command the Rear Defog Relay 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
- Ignition OFF, disconnect the R/DEFOG relay.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal J3 and ground.
- Connect a test lamp between the B+ circuit terminal J3 and the control circuit terminal K1.
- Command the Rear 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 R/DEFOG relay.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ fuse is open, test the control circuit terminal J1 for a short to ground. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
Component Testing
- Ignition OFF, disconnect the R/DEFOG relay.
- Test for 60-180 ohms between terminals 85 and 86.
- Test for infinite resistance between the following terminals:
- Install a 40-amp 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 not within the specified range, replace the relay. |
| • | 30 and 86 |
| • | 30 and 87 |
| • | 30 and 85 |
| • | 85 and 87 |
| ⇒ | If greater than the specified range, replace the relay. |
| ⇒ | If greater than the specified range, replace the relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
