B3125

DTC B3125, B3130, or B3135

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3125 00
- Left Front/Driver Door Only, Unlock Circuit

DTC B3130 00
- All Unlock Circuit

DTC B3135 00
- All Door Lock Circuit

Diagnostic Fault Information






Circuit/System Description

For vehicles without the RPO AXC/AXE door lock system, the body control module (BCM) controls the door lock, passenger door unlock and driver door unlock relays. Voltage is applied to the appropriate relay through the door lock/unlock control circuit when the BCM senses a door lock/unlock switch activation or a keyless entry lock or unlock command.

For vehicles with the RPO AXC/AXE door lock system, the BCM controls the rear door lock and rear door unlock relays. Voltage is applied to the appropriate relay through the door lock/unlock control circuit when the BCM receives a door lock/unlock command from either the driver door module or the passenger door module or a keyless entry lock or unlock command

Conditions for Running the DTC

The system voltage is 9-18 volts.

Conditions for Setting the DTC

B3125 00

The BCM detects a short to ground on the LF Door Unlock low reference circuit (Except AXC/AXE).

B3130 00

The BCM detects a short to ground on the Doors Unlock low reference circuit.

B3135 00

The BCM detects a short to ground on the Doors Locked control circuit.

Action Taken When the DTC Sets

* The BCM stores the DTC to memory.
* The power door locks will not operate.

Conditions for Clearing the DTC

* This DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 50 ignition cycles.

Circuit/System Verification

Command the driver door and passenger door lock actuators to LOCK and UNLOCK with the scan tool, the doors should LOCK and UNLOCK.

Circuit/System Testing

1. Ignition OFF, disconnect the appropriate relay.
2. Connect a test lamp between the coil control circuit terminal 85 and the coil side B+ circuit terminal 86.
3. Ignition ON, command the doors to LOCK and UNLOCK with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

^ If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

^ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the appropriate relay.

Component Testing

1. Ignition OFF, disconnect the applicable relay.
2. Test for 60-200 ohms of resistance between terminals 85 and 86.

^ If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87

^ If less than infinite resistance, replace the relay.

4. Test for less than 2 ohms of resistance between terminals 30 and 87A.

^ If greater than 2 ohms, replace the relay.

5. Install a 3A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms of resistance between terminals 30 and 87.

^ If greater than 2 ohms, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)