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 Descriptor
DTC B0283 02
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Electric Rear Defrost Circuit Short To Ground
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
The HVAC control module detects a short to ground in the relay control circuit.
Action Taken When the DTC Sets
The rear window defogger grid 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 Sunshade - Left (DH6)
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
Engine running, command the rear window defogger grid ON and OFF with a scan tool. The rear window defogger grid should turn ON and OFF when changing between the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the KR5 rear defogger relay.
2. Test for less than 10 ohms between the ground circuit terminal 85 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance
3. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
4. Engine running, command the E18 rear window defogger grid 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. If all circuits test normal, test or replace the KR5 rear defogger relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the KR5 rear defogger relay.
2. Test for 60-180 ohms between terminals 85 and 86.
• If not within the specified range, replace the KR5 rear defogger 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 KR5 rear defogger relay.
4. Install a 25 A 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 ohms between terminals 30 and 87.
• If greater than the specified range, replace the KR5 rear defogger relay.
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