Volt

DTC B0283

When the HVAC control module receives a rear window demist request from the HVAC control faceplate, the HVAC control module will supply voltage to the relay coil. Battery positive voltage is supplied at all times to the relay switched input and the relay coil is always grounded. This allows battery positive voltage from the relay switched input to flow through the switch contacts and out the relay switched output to the rear window demister grid.

Battery voltage must be between 9-16 V.

B0283 02

The HVAC control module detects a short to ground on a relay control circuit for 1 second or greater.

B0283 05

The HVAC control module detects a short to voltage or an open/high resistance a relay control circuit for 1 second or greater.

B0283 02

The rear window demister will be inoperative.

B0283 05

The rear window demister will malfunction.

Schematic Reference

Demister Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Rear Window Demister Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Vehicle ON, command the Rear Demist ON and OFF with a scan tool, the upper and lower rear window demister grids should turn ON and OFF when changing between the commanded states.

1. Vehicle OFF, disconnect the KR5 rear window demister relay.
2. Vehicle OFF, disconnect the KR4B outside wing mirror heater relay.
3. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86 of the KR4B outside wing mirror heater relay.
4. Vehicle ON, command the Rear Demist ON and OFF with a scan tool. The test lamp 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 K33 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 K33 HVAC control module.

5. Vehicle OFF, connect the KR4B outside wing mirror heater relay.
6. Vehicle ON, command the Rear Demist ON and OFF with a scan tool, DTC B0283 should not reset.

⇒	If DTC B0283 is current, test or replace the KR4B outside wing mirror heater relay.

7. If all circuits test normal, test or replace the KR5 rear window demister relay.

Relay Test

1. Vehicle OFF, disconnect the appropriate relay.
2. Test for 60-180 Ω between terminals 85 and 86.

⇒	If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified value, replace the relay.

4. Install a 3A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.