Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
DTC Descriptor
DTC B3132: All Door Unlock Circuit LowDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
BCM B+ | 1 | 1 | -- | -- |
Driver Door Lock Switch Signal | B3272 | 1 | 1 | -- |
Passenger Door Lock Switch Signal | B3272 | 1 | 1 | -- |
Driver Door Lock Control | B3127, B3137 | B3128, B3138 | 1 | -- |
Passenger Door Lock Control | B3132, B3137 | B3133, B3138 | 1 | -- |
Rear Door Lock Control | B3132, B3137 | B3133, B3138 | 1 | -- |
Driver Door Lock Switch Ground | -- | 1 | 1 | -- |
Passenger Door Lock Switch Ground | -- | 1 | 1 | -- |
1. Door Locks Malfunction | ||||
Circuit/System Description
The body control module (BCM), upon receipt of a lock switch lock signal, will provide a ground to the door latch unlock control circuit while simultaneously providing voltage to the door latch lock control circuit causing the door latch to perform the lock function. When the BCM receives a lock switch unlock signal, the BCM will provide and ground to the door latch lock control circuit while simultaneously providing voltage to the door latch unlock control circuit causing the door latch to perform the unlock function.
Conditions for Running the DTC
The system voltage must be between 9-16 volts.
Conditions for Setting the DTC
| • | Monte Carlo: The BCM detects a short to ground on the front passenger door unlock control circuit while commanding the door latches |
| • | Impala: The BCM detects a short to ground on the front passenger, left rear or right rear door unlock control circuit while commanding the door latches |
Action Taken When the DTC Sets
The power door locks will malfunction.
Conditions for Clearing the DTC
| • | This DTC will change from current to history when the fault is no longer present. |
| • | A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
Reference Information
Schematic Reference
Door Lock/Indicator Schematics
Connector End View Reference
Description and Operation
Power Door Locks Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, observe the function of the passenger door or left rear door and right rear door while commanding the Passenger Door Unlock and Door Lock with a scan tool. The doors should perform the LOCK and UNLOCK function.
| ⇒ | If the DTC is current on the Monte Carlo, refer to Monte Carlo Door Lock Malfunction |
| ⇒ | If the DTC is current on the Impala, refer to Impala Door Lock Malfunction |
Circuit/System Testing
Monte Carlo Door Lock Malfunction
- Ignition OFF, disconnect the C2 harness connector at the front passenger door lock.
- Connect a test lamp between the control circuit terminal A and ground.
- Ignition ON, command the Passenger Door Unlock with a scan tool. The test lamp should briefly illuminate during the UNLOCK command.
- If all circuits test normal, test or replace the front passenger door lock.
| ⇒ | 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 BCM. |
Impala
- Ignition OFF, disconnect the C2 harness connector at the left I/P junction block.
- Verify that a test lamp does not illuminate between the control circuit terminal B4 and B+.
- Disconnect the C2 harness connector at the right I/P junction block.
- Verify that a test lamp does not illuminate between the control circuit terminal C4 and B+.
- Disconnect the C2 harness connector at the BCM.
- Verify that a test lamp does not illuminate between the control circuit terminal A6 and B+.
| ⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, test or replace the left rear door lock. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, test or replace the appropriate door lock. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the appropriate door lock.
- Install a 20A fused jumper wire between one of the control terminals and 12V. Momentarily install a jumper wire between the other control terminal and ground. Reverse the jumper wires at least two times, the latch should perform the LOCK/UNLOCK functions.
| ⇒ | If it does not perform as specified, replace the door lock. |
Repair Instructions
| • | Control Module References for BCM replacement, setup, and programming |
