B0283

DTC B0283

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC B0283 02
- Rear Defrost Circuit Short To Ground

DTC B0283 05
- Rear Defrost Circuit High Voltage/Open

Diagnostic Fault Information






Circuit/System Description

When the HVAC control module receives a rear window defog 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 defogger grid.

Conditions for Running the DTC

Battery voltage must be between 9-16 V.

Conditions for Setting the DTC

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.

Action Taken When the DTC Sets

B0283 02

The rear window defogger will be inoperative.

B0283 05

The rear window defogger will malfunction.

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

Defogger Schematics Electrical Diagrams
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation

Rear Window Defogger Description and Operation Description and Operation
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

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

Circuit/System Testing

1. Vehicle OFF, disconnect the KR5 rear window defogger relay.
2. Vehicle OFF, disconnect the KR4B outside rearview mirror heater relay.
3. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86 of the KR4B outside rearview mirror heater relay.
4. Vehicle ON, command the Rear Defog 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 rearview mirror heater relay.
6. Vehicle ON, command the Rear Defog ON and OFF with a scan tool, DTC B0283 should not reset.

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

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

Component Testing

Relay Test
1. Vehicle OFF, disconnect the appropriate relay.
2. Test for 60-180 ohm 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 ohm between terminals 30 and 87.

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

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Control Module References Programming and Relearning for HVAC control module replacement, programming and setup