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 05
- Electric Rear Defrost Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit/System Description
The HVAC control module monitors the voltage level on the supply voltage circuit of the rear defog relay. The voltage level should be low while the rear defog relay is de-energized. The voltage will be near system voltage when the HVAC control module energizes the rear defog relay.
Conditions for Running the DTC
Battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
* The HVAC control module detects a short to battery or open/high resistance in the defog relay coil control circuit for 1 second or greater.
* A vehicle that has been converted into a hearse
Action Taken When the DTC Sets
The rear window defogger will not operate.
Conditions for Clearing the DTC
* The DTC clears when the fault is no longer detected.
* The current DTC will become history when the request for the output is removed.
* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.
Diagnostic Aids
B0283 05 will be continuously set for the vehicles converted into a hearse and cannot be cleared, ignore this code for any vehicle converted into a hearse.
Reference Information
Schematic Reference
Defogger Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Rear Window Defogger Description and Operation (Rear Window Defogger)
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
Ignition ON, command the Rear Defog Request ON and OFF with the scan tool. The rear window defogger should turn ON and OFF when changing between the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the RR DEFOG relay.
2. Test for less than 1 ohm 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. Ignition ON, command the Rear Defog Request 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 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 HVAC control module.
5. If all circuits test normal, test or replace the RR DEFOG relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the RR DEFOG relay.
2. Test for 60-180 ohms 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 25A fused jumper wire between relay terminal 85 and 12V. 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 relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for HVAC control module replacement, setup, and programming