Circuit Description
The body control module (BCM) monitors the voltage level on the control circuit of the DEFOG relay. The voltage level should be near system voltage while the DEFOG relay is de-energized. The voltage will be pulled low when the BCM energizes the DEFOG relay. The BCM tests the control circuit of the DEFOG relay every 125 milliseconds.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B0283 Electric Rear Defrost Circuit
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
One of the following conditions will cause this DTC to set:
| • | The BCM detects a high voltage level on the control circuit of the DEFOG relay, while the relay is energized. |
| • | The BCM detects a low voltage level or an open on the control circuit of the DEFOG relay, when commanding the relay ON. |
Action Taken When the DTC Sets
The rear window defogger will be disabled until the condition is no longer present.
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 a repeat of the malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the DEFOG relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the coil side of the DEFOG relay. The HVAC fuse supplies power to the coil side of the DEFOG relay.
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Verifies that the BCM is providing ground to the DEFOG relay.
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Tests if ground is constantly being applied to the DEFOG relay.
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Tests for an open on the control circuit of the DEFOG relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Defogger Schematics Connector End View Reference: Window Systems Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Do you hear a click when you command the DEFOG relay ON and OFF? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 | |
Test the control circuit of the DEFOG relay for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 | |
7 | Test the control circuit of the DEFOG relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the DEFOG relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
10 | Repair an open or high resistance in ignition voltage circuit of the DEFOG relay coil. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the DEFOG relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
