B0283

DTC B0283

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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

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

B0283 02

The HVAC control module detects a short to ground in the DEFOG relay coil control circuit for 1 second or greater.

B0283 05

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.

Action Taken When the DTC Sets

1. The HVAC control module stores the DTC to memory.
2. The rear window defogger will not operate.

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.

Circuit/System Verification

Command the rear window defogger 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 REAR DEFOG relay.
2. Test for less than 1.0 ohm between the ground circuit terminal 85 and ground.

^ If greater than the specified range, test the relay coil 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 defogger grid ON and OFF by pressing and depressing the rear defogger switch. 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 REAR DEFOG relay.

Repair Instructions

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

* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)