For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC B3140: Driver Unlock Switch Circuit
DTC B3145: Passenger Unlock Switch Circuit
DTC B3150: Driver Lock Switch Circuit
DTC B3155: Right Front Lock Switch Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Relay Switch B+ | 1, 2, 3 | 1, 2, 3 | -- | --
Door Unlock Relay Control | B3130 | B3130 | B3130 | --
Driver Door Relay Unlock Control | B3125 | B3125 | B3125 | --
Door Lock Relay Control | B3135 | B3135 | -- | --
Driver Door Lock Switch Lock Signal | B3150 | B3150 | B3150 | --
Driver Door Lock Switch Unlock Signal | B3140 | B3140 | B3140 | --
Passenger Door Lock Switch Lock Signal | B3155 | B3155 | B3155 | --
Passenger Door Lock Switch Unlock Signal | B3145 | B3145 | B3145 | --
Door Lock Switch Ground | -- | 1, 2, 3 | 1, 2, 3 | --
I/P Fuse Block Ground | -- | 1, 2, 3 | 1, 2, 3 | --
1. Door Locks Inoperative 2. Driver Door Unlock Inoperative 3. Door Unlock Inoperative

### Circuit/System Description

The body control module (BCM) supplies and monitors a reference voltage to the door lock switch through the door lock switch lock/unlock signal circuit. The door lock switch also receives a constant ground source. If a door lock switch is placed in the lock position or unlock position, the reference voltage is taken directly to ground and the BCM detects 0.0 volts on the signal circuit.

### Conditions for Running the DTC

The system voltage must be between 9-16 volts.

### Conditions for Setting the DTC

#### B3140 or B3150

The BCM detects a short to ground in the driver door lock switch lock or unlock signal circuits.

#### B3145 or B3155

The BCM detects a short to ground in the passenger door lock switch lock or unlock signal circuits.

### 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 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

Vehicle Access Connector End Views

#### Description and Operation

Power Door Locks Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate door lock switch.
2. Ignition ON, verify the appropriate scan tool Lock Sw parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal L for a short to ground. If the circuit tests normal, replace the BCM.

3. Verify the appropriate scan tool Unlock Sw parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal U for a short to ground. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the appropriate door lock switch.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the applicable door lock switch.
2. Test for infinite resistance between the signal terminals U and L and the ground terminal C with the switch in the at rest position.

⇒ | If less than infinite resistance, replace the applicable door lock switch.

3. Test for less than 2 ohms of resistance between the signal terminal L and the ground terminal C with the switch in the lock position.

⇒ | If greater than 2 ohms, replace the applicable door lock switch.

4. Test for less than 2 ohms of resistance between the signal terminal U and the ground terminal C with the switch in the unlock position.

⇒ | If greater than 2 ohms, replace the applicable door lock switch

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Door Lock Switch Replacement

• | Control Module References for BCM replacement, setup, and programming