For 1990-2009 cars

### Circuit Description

The body control module (BCM) controls the DEFOG relay circuit. When the ignition switch is in RUN position and the operator has depressed the defogger switch, the BCM provides power to the DEFOG relay control circuit.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B0283 Electric Rear Defrost

### Conditions for Running the DTC

The system voltage must be between 9-16 volts.

### Conditions for Setting the DTC

The BCM detects a short to battery positive voltage in the DEFOG relay control circuit when the BCM is trying to energize the relay.

The BCM detects that the DEFOG relay control circuit is open.

The condition above must be present for more than 1 second.

### Action Taken When the DTC Sets

The BCM stores DTC B0283 in memory. The DEFOG will not operate.

### Conditions for Clearing the DTC

• | A current DTC clears when the malfunction is no longer present.

• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without repeat of the malfunction.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Tests for battery positive voltage at the coil side of the rear window defogger relay. The EF25 (10A) fuse supplies power to the coil side of the DEFOG relay.

2. Tests the control circuit side of the DEFOG relay for faults that cause DTC B0283.

3. Listen for an audible click when the DEFOG relay operates. Command both the ON and OFF states.

4. Verifies that the BCM is providing ground to the DEFOG relay.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Remove the DEFOG relay.
2. Connect a test lamp between the DEFOG relay EF25 (10A) fused voltage supply circuit and ground at the DEFOG relay socket.
3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 3

Go to Step 8

3 |

1. Turn OFF the ignition.
2. Test the control circuit of the DEFOG relay for a short to battery positive voltage and ground.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 4

4 |

1. Connect a test lamp between the EF25 (10A) fused voltage supply circuit and the control circuit of the DEFOG relay socket.
2. Turn ON the ignition, with the engine OFF.
3. Using a scan tool, command the relay ON then OFF.

Does the test lamp turn ON and OFF?

--

Go to Step 6

Go to Step 5

5 | Test the control circuit of the DEFOG relay for an open. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7
6 | Inspect for poor connections and terminal damage at the relay socket. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9
7 | Inspect for poor connections at the harness connector of the body control module (BCM). Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10
8 | Repair the short to ground, poor connection or an open in the EF25 (10A) fused voltage supply circuit. Did you complete the repair? | -- | Go to Step 11 | --
9 | Replace the DEFOG relay. Did you complete the replacement? | -- | Go to Step 11 | --
10 | Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
11 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK