| • | 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  | 
|---|---|---|---|---|
K2 Relay B+  | 2  | 2  | --  | --  | 
Rear Defrost Switch Signal  | B3743 5A  | 2  | 2  | --  | 
Rear Defog Relay Control  | B0283 00  | B0283 00  | B0283 00  | --  | 
Rear Defog Indicator Control  | B0969 02  | 3  | B0969 01  | --  | 
Rear Window Defogger Grid Control  | 2  | 2  | 1  | --  | 
Rear Window Defogger Grid Ground  | --  | 2  | 2  | --  | 
1. Rear Defogger Always On 2. Rear Defogger Inoperative 3. Rear Defogger Indicator Inoperative  | ||||
The rear fuse block monitors the voltage level on the supply voltage circuit of the K2 relay. The voltage level should be low while the K2 relay is de-energized. The voltage will be near system voltage when the rear fuse block energizes the K2 relay.
Battery voltage must be between 9-16 volts.
When the rear fuse block detects a fault in the relay control 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
Ignition ON, command the REC Heated Rear Window Test 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 is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the rear fuse block. | 
| ⇒ | 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 rear fuse block. | 
| ⇒ | 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 rear fuse block replacement, setup, and programming |