Circuit Description
The body control module (BCM), upon receipt of a door lock switch unlock signal or a keyless unlock command, will supply battery voltage to the driver door lock actuator unlock control circuit to unlock the driver door.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3127 Left Front/Driver Door Only Unlock Circuit Low
Conditions for Running the DTC
| • | Battery voltage is between 9-16 volts. |
| • | The BCM supplies battery voltage to the driver door lock actuator unlock control circuit. |
Conditions for Setting the DTC
| • | The BCM does not detect a driver door unlock relay feedback on the driver door lock actuator unlock control circuit. |
| • | The conditions above must be present for more than 0.3 seconds. |
Action Taken When the DTC Sets
| • | The BCM sets DTC B3127 as current. |
| • | The driver door lock actuator will not lock or unlock. |
Conditions for Clearing the DTC
| • | When the driver door unlock relay feedback is detected by the BCM during a driver door unlock operation |
| • | A current DTC will go to history DTC status after the ignition has been cycled. |
| • | A history DTC will clear after 100 consecutive fault-free ignition cycles. |
| • | A scan tool may be used to clear the DTC. |
Diagnostic Aids
If the DTC B3127 is accompanied by DTC B3132 and B3137, the fault may be any of the following:
| • | An open BCM PWR 15-amp fuse, which could be caused by any of the following: |
| - | The BCM is shorted to ground internally. |
| - | Any of the door lock actuator lock or unlock control circuits are shorted to ground. |
| • | The BCM has an internal open. |
If DTC B3127 is set as current and DTCs B3132 and B3137 will not set with multiple lock and unlock switch activations, the BCM is internally open.
Step | Action | Yes | No |
|---|---|---|---|
Connector End View Reference: Power Door Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Is DTC B3127 set as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
3 | Operate a door lock switch to the lock and unlock position multiple times. Did DTCs B3132 and B3137 also set as current? | Go to Step 4 | Go to Step 6 |
4 | Is the body control module (BCM) PWR 15-amp fuse open? | Go to Step 5 | Go to Step 6 |
5 | Test for a short to ground in the driver door lock actuator unlock control, the passenger door lock actuator unlock control, and the door lock actuator lock control circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 8 | Go to Step 6 |
6 | Inspect for poor connections at the 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 8 | Go to Step 7 |
7 | 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 8 | -- |
8 |
Does the DTC reset? | Go to Step 2 | System OK |
