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 |
|---|---|---|---|---|
Relay B+ | B0283 05 | B0283 05 | -- | -- |
Rear Defog Relay Control | B0283 02 | B0283 05 | B0283 05 | -- |
Rear Defogger Grid Control | 2 | 2 | 1 | -- |
Rear Window Defogger Grid Ground | -- | 2 | 2 | -- |
1. Rear defogger always On 2. Rear defogger inoperative | ||||
Circuit/System Description
When the rear defog switch is pressed, a signal is sent to the body control module (BCM) which energizes the rear defog relay by providing a ground to the control circuit of the rear defog relay. This allows battery positive voltage from the relay switched input 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 BCM detects a short to ground in the relay coil control circuit.
B0283 05
The BCM detects a short to voltage or an open/high resistance in the relay control circuit.
Action Taken When the DTC Sets
B0283 02
The rear window defogger will operate continuously.
B0283 05
The rear window defogger 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
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 window defogger 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
Rear Defogger Malfunction
- Ignition OFF, disconnect the REAR/FOG relay.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- Command the rear window defogger 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/FOG 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+ curcuit fuse is open, test the control circuit terminal 87 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
Relay Test
- Ignition OFF, disconnect the REAR/FOG 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 |
