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
- Electric Rear Defrost Circuit Short To Ground
DTC B0283 05
- Electric Rear Defrost Circuit Short To Battery or 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
When the relay is actively commanded by the HVAC control module.
Conditions for Setting the DTC
B0283 02
The HVAC control module detects a short to ground in the relay control circuit.
B0283 05
The HVAC control module detects a short to voltage or an open/high resistance in the relay control circuit.
Action Taken When the DTC Sets
* If B0283 02 is current, the rear window defogger grid will operate continuously.
* If B0283 05 is current, the rear window defogger grid will be inoperative.
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 Outside Rearview Mirror - Driver
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 Control Module References for scan tool information
Circuit/System Verification
1. Engine Running.
2. Verify the rear window defogger turns ON and OFF when commanding the rear window defogger ON and OFF with a scan tool.
• If the rear window defogger does not turn ON or OFF
Refer to Circuit/System Testing
• If the rear window defogger turns ON and OFF
3. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the KR5 rear defogger relay. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 1 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Connect a test lamp between the control circuit terminal 2 and the ground circuit terminal 1, Engine Running.
4. Verify the test lamp turns ON and OFF when commanding the rear window defogger ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module, Engine Running.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K33 HVAC control module.
• If the test lamp turns ON and OFF
5. Test or replace the KR5 rear defogger relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the KR5 rear defogger relay.
2. Test for 60-200 ohms between terminals 1 and 3.
• If less than 60 ohms or greater than 200 ohms
Replace the KR5 rear defogger relay.
• If between 60-200 ohms
3. Test for infinite resistance between the terminals listed below:
* 4 and 3
* 4 and 5
* 4 and 1
* 5 and 1
• If less than infinite resistance
Replace the KR5 rear defogger relay.
• If infinite resistance
4. Install a 3 A fused jumper wire between relay terminal 3 and 12 V. Install a jumper wire between relay terminal 1 and ground.
5. Test for less than 2 ohms between terminals 4 and 5.
• If 2 ohms or greater
Replace the KR5 rear defogger relay.
• If less than 2 ohms
6. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for HVAC control module replacement, setup and programming