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
1. Vehicle ON.
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. Vehicle OFF, disconnect the KR5 rear defogger relay.
2. Disconnect the KR4B outside rear view mirror heater relay.
3. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86 at the KR4B outside rear view mirror heater relay, Vehicle ON.
4. Verify the test lamp turns ON and OFF commanding the rear window defogger ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Vehicle 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. Vehicle OFF, disconnect the harness connector at the K33 HVAC control module, Vehicle ON.
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 or the KR4B outside rear view mirror heater relay.
Component Testing
Rear View Mirror Heater Relay Test
1. Vehicle OFF, disconnect the KR4B outside rear view mirror heater relay.
2. Test for 60-180 ohms between terminals 85 and 86.
• If less than 60 ohms or greater than 180 ohms
Replace the KR4B outside rear view mirror heater relay.
• If between 60-180 ohms
3. Test for infinite resistance between the terminals listed below:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If less than infinite resistance
Replace the KR4B outside rear view mirror heater relay.
• If infinite resistance
4. Install a 3 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
5. Test for less than 2 ohms between terminals 30 and 87.
• If 2 ohms or greater
Replace the KR4B outside rear view mirror heater relay.
• If less than 2 ohms
6. All OK
Rear Defogger Relay Test
1. Vehicle OFF, disconnect the KR5 rear defogger relay.
2. Test for 60-200 ohms between terminals 41 and 40.
• 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:
* 41 and 43
* 41 and 42
* 40 and 43
* 40 and 42
• 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 41 and 12 V. Install a jumper wire between relay terminal 40 and ground.
5. Test for less than 2 ohms between terminals 43 and 42.
• 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 Programming and Relearning for HVAC control module replacement, programming and setup