• | 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. |
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 |
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.
Battery voltage must be between 9-16 volts.
The BCM detects a short to ground in the relay coil control circuit.
The BCM detects a short to voltage or an open/high resistance in the relay control circuit.
The rear window defogger will operate continuously.
The rear window defogger will be inoperative.
• | 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. |
Rear Window Defogger Description and Operation
Control Module References for scan tool information
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.
⇒ | 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. |
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup and programming |