Circuit Description
The body control module (BCM) grounds the control side of the left rear power window down relay upon receiving a class 2 message from the driver door module (DDM).
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3820 Left Rear Window Down Control Circuit
Conditions for Running the DTC
| • | Battery voltage is between 9-16 volts. |
| • | The BCM has received a class 2 message from the DDM and has grounded the left rear power window down relay control circuit. |
Conditions for Setting the DTC
| • | When the BCM has grounded the left rear power window down relay control circuit and the control circuit is shorted to battery positive voltage. |
| • | The above condition is met for 250 milliseconds. |
Action Taken When the DTC Sets
The left rear power window will be inoperative from both the driver and left rear power window switches.
Conditions for Clearing the DTC
When the fault is no longer present, the BCM changes the current DTC to a history DTC. The BCM will clear the history DTC after 50 fault free ignition cycles.
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 left rear power window 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 left rear power window down relay.
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Verifies that the BCM is providing ground to the left rear power window down relay.
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Tests if ground is constantly being applied to the left rear power window down relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Power Window Schematics Connector End View Reference: Power Door Systems Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the left rear power window up relay turn ON and OFF with each command? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | 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 | |
6 | Test the control circuit of the left rear power window down relay for a short to voltage . Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the left rear power window down relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the left rear power window switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. 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 body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
10 | Repair the open or short to ground in the battery positive voltage circuit of the left rear power window switch. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the left rear power window switch. Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems 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 |
