GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Door Lock/Indicator Schematics

Connector End View Reference: Vehicle Access Connector End Views

DEFINITION: This diagnostic should be used to diagnose a failure of the driver door lock actuator (lock, unlock or both).

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Actuate all the door lock switches to both the lock and unlock positions.

Did the cargo door lock and unlock from all of the switches?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Did the passenger doors lock and unlock from all of the switches?

Go to Step 4

Go to Power Door Locks Inoperative - One Door or Switch

4

Is the vehicle equipped with keyless entry?

Go to Step 5

Go to Step 12

5

Did the cargo door lock?

Go to Step 7

Go to Step 6

6

Did the cargo door unlock?

Go to Step 9

Go to Step 12

7

  1. Remove the cargo door unlock relay from the fuse block.
  2. Connect a test lamp between battery positive voltage and the cargo door unlock relay control circuit at the fuse block.
  3. Install a scan tool.
  4. Command the doors to unlock.

Did the test lamp illuminate?

Go to Step 8

Go to Step 14

8

  1. Monitor the passenger door unlock input data value on the scan tool.
  2. Actuate a door lock switch to the unlock position.

Did the data value change from inactive to active when the switch was actuated?

Go to Step 10

Go to Step 16

9

  1. Remove the cargo door unlock relay.
  2. Connect a test lamp between the cargo door unlock relay ground circuit at the fuse block and battery positive voltage.

Did the test lamp illuminate?

Go to Step 15

Go to Step 22

10

Connect a test lamp between the battery positive voltage circuit on the coil side of the cargo door lock relay and ground.

Did the test lamp illuminate?

Go to Step 11

Go to Step 23

11

Connect a test lamp between the battery positive voltage circuit on the switched side of the cargo door lock relay and ground.

Did the test lamp illuminate?

Go to Step 15

Go to Step 23

12

  1. Disconnect the cargo door lock actuator.
  2. Connect a test lamp between the door lock actuator lock circuit and ground.
  3. Actuate a door lock switch to the lock position.

Did the test lamp illuminate?

Go to Step 13

Go to Step 20

13

  1. Connect a test lamp between the door lock actuator unlock circuit and ground.
  2. Actuate a door lock switch to the unlock position.

Did the test lamp illuminate?

Go to Step 17

Go to Step 21

14

Test for an open in the cargo door unlock relay control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 26

Go to Step 18

15

Inspect for poor connections at the cargo door unlock relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 26

Go to Step 19

16

Check for an open in the door unlock signal circuit between the body control module (BCM) and the door lock switches. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 26

Go to Step 18

17

Inspect for poor connections at the cargo door lock actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 26

Go to Step 24

18

Inspect for poor connections at the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 26

Go to Step 25

19

Replace the cargo door unlock relay. Refer to Relay Replacement .

Did you complete the repair?

Go to Step 26

--

20

Repair the open in the door lock control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 26

--

21

Repair the open in the door unlock control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 26

--

22

Repair the open in the cargo door lock relay ground circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 26

--

23

Repair the open in the cargo door lock relay battery positive voltage circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 26

--

24

Replace the door lock actuator. Refer to Power Door Lock Actuator Replacement .

Did you complete the repair?

Go to Step 26

--

25

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the repair?

Go to Step 26

--

26

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2