• | 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 provide an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Rear Defog Relay Switch B+ | 2 | 2 | -- | -- |
Rear Defog Relay Control | B0283 06 | B0283 05, B0283 06 | B0283 05 | -- |
Rear Window Defogger Grid Control | 2 | 2 | 1 | -- |
Rear Defog Relay Ground | 1 | B0283 05, B0283 06 | 2 | -- |
Rear Window Defogger Grid Ground | -- | 2 | 2 | -- |
1. Rear Defogger Always ON 2. Rear Defogger Inoperative |
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. 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.
Battery voltage must be between 9-16 volts.
The HVAC control module detects a short to battery or open/high resistance in the defog relay coil control circuit or an open/high resistance in the relay coil ground circuit for 1 second or greater.
The HVAC control module detects a short to ground or open/high resistance in the defog relay coil control circuit or an open/high resistance in the relay coil ground circuit for 1 second or greater.
The rear window defogger will not operate.
• | 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
Command the Rear Defog Request ON and OFF with the scan tool. The rear window defogger should turn ON and OFF when changing between the commanded states.
⇒ | 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. |
⇒ | If not within the specified range, replace the relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If not the specified value, 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 HVAC control module replacement, setup, and programming |