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Home >> Buick >> 2013 >> Regal L4-2.0L Turbo >> Repair and Diagnosis >> Body and Frame >> Locks >> Testing and Inspection >> Power Door Locks Malfunction

Power Door Locks Malfunction





Power Door Locks Malfunction

Diagnostic Instructions

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

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

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) powers the reversible door latch assemblies by providing battery positive voltage and ground to the appropriate lock and unlock control circuits of the door latch assemblies. The lock and unlock control circuits of the rear doors and passenger door latch assemblies are all connected together. When the door latch assemblies are not active, all actuator lock and unlock control circuits are supplied a floating voltage door driver by the BCM. Transitioning of the lock actuators to the lock or unlocked position depends upon which control circuits receive voltage and which control circuits receive ground.

Diagnostic Aids

Verify the smooth and consistent mechanical operation of each part of the door latch system prior to performing extensive electrical diagnostics

Any door that does not function smoothly or consistently, refer to Door Will Not Open/Close, Door Binding, or Locks, Handles, or Cylinders Do Not Function Door Will Not Open/Close, Door Binding, or Locks, Handles, or Cylinders Do Not Function.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views Sunshade - Left

Description and Operation

Power Door Locks Description and Operation Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify the scan tool BCM Central Door Lock Switch on Console parameter changes from Inactive to Lock and Unlock when cycling the central door lock switch between LOCK and UNLOCK.

• If the parameter does not change
Refer to Circuit/System Testing - Central Door Lock Switch Malfunction.

• If the parameter changes

3. Verify all vehicle doors LOCK and UNLOCK when commanding the All Doors Lock/Unlock with a scan tool.

• If only the driver door LOCK or UNLOCK functions do not work
Refer to Circuit/System Testing - Driver Door Lock Malfunction.

• If one or more, but not all, passenger door LOCK or UNLOCK functions do not work
Refer to Circuit/System Testing - Passenger Door Lock Malfunction.

• If all door LOCK and UNLOCK functions do not work
Refer to Circuit/System Testing - All Door Lock Inoperative.

• If the LOCK and UNLOCK function for all doors works

4. All OK.

Circuit/System Testing

Central Door Lock Switch Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S48C multifunction switch 1-instrument panel. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 10 ohms between the ground circuit terminal 7 and ground.

• If 10 ohms or greater

1. Ignition OFF.

2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, repair the open/high resistance in the ground connection.

• If less than 10 ohms

3. Ignition ON.

4. Verify the scan tool Central Door Lock Switch on Console parameter is Inactive.

• If not Inactive

1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module.

2. Test for infinite resistance between the signal circuit terminal 12 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

3. Test for infinite resistance between the signal circuit terminal 18 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the K9 body control module.

• If Inactive

5. Install a 3 A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 7.

6. Verify the scan tool Central Door Lock Switch on Console parameter is Unlock.

• If not Unlock

1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module, ignition ON.

2. Test for less than 1 V between the signal circuit terminal 18 and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If Unlock

7. Install a 3 A fused jumper wire between the signal circuit terminal 11 and the ground circuit terminal 7.

8. Verify the scan tool Central Door Lock Switch on Console parameter is Lock.

• If not Lock

1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module, ignition ON.

2. Test for less than 1 V between the signal circuit terminal 12 and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If Lock

9. Test or replace the S48C multifunction switch 1-instrument panel.

Driver Door Lock Malfunction

1. Ignition OFF, verify the harness connector is firmly seated and secure for the A23D door latch assembly-driver.

• If the harness connector not seated or secure
Firmly seat and secure the harness connector at the A23D door latch assembly-driver.

• If the harness connector is firmly seated and secure

2. Disconnect the harness connector at the A23D door latch assembly-driver. Ignition ON.

Note: Leaving the DMM connected between a control circuit and ground for greater than 20 seconds will cause the K9 body control module to interpret the test as a system fault and will cause the voltage on the control circuit to drop to 0 V. If the voltage drops to 0 V, operate the door locks using the central door lock switch to restore the voltage for testing.

3. Test for greater than 7 V between the control circuit terminal 3 and ground.

• If 7 V or less

1. Ignition OFF, disconnect the X6 harness connector at the K9 body control module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance on the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If greater than 7 V

Note: Leaving the DMM connected between a control circuit and ground for greater than 20 seconds will cause the K9 body control module to interpret the test as a system fault and will cause the voltage on the control circuit to drop to 0 V. If the voltage drops to 0 V, operate the door locks using the central door lock switch to restore the voltage for testing.

4. Test for greater than 7 V between the control circuit terminal 2 and ground.

• If 7 V or less

1. Ignition OFF, disconnect the X6 harness connector at the K9 body control module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance on the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If greater than 7 V

5. Test or replace the A23D door latch assembly-driver.

Passenger Door Lock Malfunction

1. Ignition OFF, verify the harness connector is firmly seated and secure for the appropriate passenger or rear A23 door latch assembly.

• If the harness connector not seated or secure
Firmly seat and secure the harness connector at the passenger or rear A23 door latch assembly.

• If the harness connector is firmly seated and secure

2. Disconnect the harness connector at the appropriate passenger or rear A23 door latch assembly. Ignition ON.

Note: Leaving the DMM connected between a control circuit and ground for greater than 20 seconds will cause the K9 body control module to interpret the test as a system fault and will cause the voltage on the control circuit to drop to 0 V. If the voltage drops to 0 V, operate the door locks using the central door lock switch to restore the voltage for testing.

3. Test for greater than 7 V between the control circuit terminal listed below and ground:

* A23P door latch assembly-passenger - control circuit terminal 7

* A23P door latch assembly-passenger - control circuit terminal 8

* A23RR door latch assembly-right rear - control circuit terminal 7

* A23RR door latch assembly-right rear - control circuit terminal 8

* A23LR door latch assembly-left rear - control circuit terminal 2

* A23LR door latch assembly-left rear - control circuit terminal 3

• If 7 V or less

1. Ignition OFF, disconnect the X6 harness connector at the K9 body control module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance on the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If greater than 7 V

4. Test or replace the A23 door latch assembly.

All Door Locks Inoperative

1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module, ignition ON.

2. Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF.

2. Test for less than 2 ohms in the B+ circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF.

2. Test for infinite resistance between the B+ circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Disconnect the harness connector at each of the A23 door latch assemblies.

4. Test for infinite resistance between each control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the appropriate A23 door latch assembly.

• If the test lamp illuminates

3. Ignition OFF, connect the X2 harness connector at the K9 body control module. Disconnect the harness connector at the A23D door latch assembly-driver, ignition ON.

Note: Leaving the DMM connected between a control circuit and ground for greater than 20 seconds will cause the K9 body control module to interpret the test as a system fault and will cause the voltage on the control circuit to drop to 0 V. If the voltage drops to 0 V, operate the door locks using the central door lock switch to restore the voltage for testing.

4. Test for greater than 7 V between the control circuit terminal 2 and ground.

• If 7 V or less

1. Ignition OFF, disconnect the KR113 child security lock disable relay.

2. Disconnect the X6 harness connector at the K9 body control module.

3. Test for infinite resistance between the control circuit terminal listed below and ground:

* KR113 child security lock disable relay - control circuit terminal 2

* KR113 child security lock disable relay - control circuit terminal 3

* K9 body control module - control circuit terminal 1 X6

* K9 body control module - control circuit terminal 4 X6

• If less than infinite resistance, repair the short to ground on the circuit.

1. Ignition OFF, connect the KR113 child security lock disable relay.

2. Test for infinite resistance between the K9 body control module control circuit terminal 2 X6 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, test or replace the KR113 child security lock disable relay.

• If greater than 7 V

5. Replace the K9 body control module.

Component Testing

Central Door Lock Switch

1. Ignition OFF, disconnect the harness connector at the S48C multifunction switch 1-instrument panel.

2. Test for infinite resistance between the signal terminal 9 and the ground terminal 7 with the switch in the open position.

• If less than infinite resistance
Replace the S48C multifunction switch 1-instrument panel.

• If infinite resistance

3. Test for infinite resistance between the signal terminal 11 and the ground terminal 7 with the switch in the open position.

• If less than infinite resistance
Replace the S48C multifunction switch 1-instrument panel.

• If infinite resistance

4. Test for less than 2 ohms between the signal terminal 11 and the ground terminal 7 with the switch in the Lock position.

• If 2 ohms or greater
Replace the S48C multifunction switch 1-instrument panel.

• If less than 2 ohms

5. Test for less than 2 ohms between the signal terminal 9 and the ground terminal 7 with the switch in the Unlock position.

• If 2 ohms or greater
Replace the S26 hazard warning switch.

• If less than 2 ohms

6. All OK

Door Latch Test

1. Ignition OFF, disconnect the harness connector at the appropriate A23 door latch assembly.

2. Install a 25 A fused jumper wire between one of the control terminals and 12 V. Momentarily install a jumper wire between the other control terminal and ground. Reverse the jumper wires at least two times, the A23 door latch assembly should perform the LOCK and UNLOCK function.

• If the actuator does not perform the LOCK and UNLOCK function
Replace the A23 door latch assembly.

• If the actuator performs the LOCK and UNLOCK function

3. All OK

Relay Test

1. Ignition OFF, disconnect the KR113 child security lock disable relay.

2. Test for 60-200 ohms between terminals 1 and 3.

• If less than 60 ohms or greater than 200 ohms
Replace the KR113 child security lock disable relay.

• If between 60-200 ohms

3. Test for infinite resistance between the terminals listed below:

* 4 and 3

* 4 and 5

* 4 and 1

* 5 and 1

• If less than infinite resistance
Replace the KR113 child security lock disable relay.

• If infinite resistance

4. Install a 3 A fused jumper wire between relay terminal 3 and 12 V. Install a jumper wire between relay terminal 1 and ground.

5. Test for less than 2 ohms between terminals 4 and 5.

• If 2 ohms or greater
Replace the KR113 child security lock disable relay.

• If less than 2 ohms

6. All OK

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Hazard Warning Switch Replacement Service and Repair

* Front Side Door Lock Replacement Front Side Door Lock Replacement

* Rear Side Door Lock Replacement Rear Side Door Lock Replacement

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

* Control Module References Control Module References for BCM replacement, programming and setup

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