Diagnostic Routine B

Diagnostic Routine B

Diagnostic Overview

A Single or More Than One Door Lock Is Inoperative

Refer to Wiring Diagram Set 117 for schematic and connector information Electrical Diagrams.

Normal Operations and Fault Conditions

The BCM (Body Control Module) supplies voltage to the lock all relay, the unlock driver door relay or unlock all relay based upon input from the door lock control switches, the RKE (Remote Keyless Entry) transmitter, or the keyless entry keypad. Upon a lock request, the BCM (Body Control Module) supplies voltage on the all door lock circuit and ground on the driver and passenger door unlock circuits. Upon an unlock request, the voltage and ground are reversed on the previously listed circuits. When the door lock and unlock relays are not energized they are connected to ground. A dedicated BCM (Body Control Module) ground circuit is provided only for the lock and unlock relays.

NOTE: The lock all, unlock driver door, and the unlock all relays are internal to the BCM (Body Control Module) and are non-serviceable.

Visual Inspection and Diagnostic Pre-checks

- Binding door lock rod

Special Tool(s)






Pinpoint Test

1. CHECK THE DOOR LATCH FOR BINDING

1. Lock and unlock the inoperative door lock using the door lock rod.

Does the door lock and unlock?








2. CHECK THE LOCK ROD FOR BINDING

1. Operate the door lock rod manually while observing the door lock rod for any binding or if the rod is bent.

Is the door lock rod bent or binding?








3. CHECK THE ALL LOCK OUTPUT CIRCUIT FOR VOLTAGE
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test lamp recommended in the Special Tools table at the beginning or electrical equivalent. To avoid connector terminal damage, use the Rotunda Flex Probe kit for the test light probe connection to the vehicle. Do not use the test lamp probe directly on any connector.

1. Ignition OFF.

2. Disconnect Inoperative Door Lock Actuator.

3. NOTE: The BCM (Body Control Module) only supplies voltage to the actuator momentarily. It is important to monitor the test light while pressing LOCK on the door lock control switch.
While pressing the door lock control switch in the LOCK position, monitor the test light.





Does the test light momentarily illuminate?








4. CHECK THE UNLOCK OUTPUT CIRCUIT FOR VOLTAGE
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test lamp recommended in the Special Tools table at the beginning or electrical equivalent. To avoid connector terminal damage, use the Rotunda Flex Probe kit for the test light probe connection to the vehicle. Do not use the test lamp probe directly on any connector.

1. NOTE: The BCM (Body Control Module) only supplies voltage to the actuator momentarily. It is important to monitor the test light while pressing UNLOCK on the door lock control switch.
While pressing the door lock control switch in the UNLOCK position, monitor the test light.





Does the test light momentarily illuminate?








5. CHECK THE UNLOCK OUTPUT CIRCUIT FOR AN OPEN

1. Disconnect BCM (Body Control Module) C2280D.

2. Measure:





Is the resistance less than 3 ohms?








6. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Ignition OFF.

2. Disconnect all the BCM (Body Control Module) connectors.

3. Repair:

- corrosion, (install new connectors or terminals- clean module pins)
- damaged or bent pins- install new terminals pins
- pushed-out pins- install new pins as necessary

4. Connect all the BCM (Body Control Module) connectors and make sure they seat correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?