GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Classic - 2WD 🢒 Body Systems 🢒 Vehicle Access 🢒 Power Door Locks Inoperative

Power Door Locks Inoperative Front

Step

Action

Yes

No

Schematic Reference: Door Lock/Indicator Schematics

Connector End View Reference: Vehicle Access Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Activate the door lock switches to the lock and unlock positions.

Do the driver and front passenger doors lock and unlock?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Do the door lock switches lock and unlock at least one of the front door lock actuators?

Go to Step 4

Go to Step 9

4
  1. Disconnect the inoperative door lock actuator.
  2. With a test lamp connected to a good ground, probe the door lock actuator lock circuit at the door lock actuator harness connector.
  3. Activate a door lock switch to lock position.

Does the test lamp illuminate?

Go to Step 5

Go to Step 7

5
  1. With a test lamp connected to a good ground, probe the door lock actuator unlock circuit at the door lock actuator harness connector.
  2. Activate a door lock switch to unlock position.

Does the test lamp illuminate?

Go to Step 6

Go to Step 8

6
  1. Connect a test lamp between the door lock actuator lock and unlock circuits at the door lock actuator harness connector.
  2. Activate a door lock switch to both the lock and unlock positions.

Does the test lamp illuminate in both positions?

Go to Step 10

Go to Step 9

7

Test for an open or short to ground in the door lock actuator lock circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Test for an open or short to ground in the door lock actuator unlock circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

9

Inspect for poor connections at the harness connector of the appropriate door module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for poor connections at the harness connector of the 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 13

Go to Step 12

11

Replace the appropriate door module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the repair?

Go to Step 13

--

12

Replace the appropriate door lock actuator. Refer to Front Side Door Lock Actuator Replacement.

Did you complete the repair?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Power Door Locks Inoperative Rear

Step

Action

Yes

No

Schematic Reference: Door Lock/Indicator Schematics

Connector End View Reference: Vehicle Access Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Activate the front door lock switches to the lock and unlock positions.

Do both rear passenger doors lock and unlock?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is there only one door lock actuator that is inoperative?

Go to Power Door Locks Inoperative - One Door or Switch

Go to Step 4

4

Are the rear door lock actuators inoperative for both lock and unlock?

Go to Step 6

Go to Step 5

5

Do the rear door lock actuators lock?

Go to Step 17

Go to Step 12

6

Is the LOCKS fuse open?

Go to Step 24

Go to Step 7

7
  1. Remove the door unlock relay.
  2. Connect a test lamp to a good ground.
  3. Probe the door unlock relay coil battery supply voltage circuit.

Does the test lamp illuminate?

Go to Step 8

Go to Step 27

8
  1. Connect a test lamp to battery positive voltage.
  2. Probe the door actuator unlock control circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

9
  1. Install the rear door unlock relay.
  2. Remove the rear door lock relay.
  3. Connect a test lamp to battery positive voltage.
  4. Probe the door lock actuator lock control circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 11

Go to Step 27

10
  1. Connect a test lamp to battery positive voltage.
  2. Probe the rear door unlock relay control circuit.

Does the test lamp illuminate?

Go to Step 22

Go to Step 26

11
  1. Connect a test lamp to battery positive voltage.
  2. Probe the rear door lock relay control circuit.

Does the test lamp illuminate?

Go to Step 23

Go to Step 25

12
  1. Remove the rear door lock relay.
  2. Connect a test lamp to a good ground.
  3. Probe the battery positive voltage circuit (high current) cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 13

Go to Step 27

13

With the test lamp connected to a good ground, probe the lock relay control circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 22

Go to Step 14

14
  1. Connect a test lamp to battery positive voltage.
  2. Probe the lock relay control circuit cavity in the rear fuse block.
  3. Activate a door lock switch to the lock position.

Does the test lamp illuminate?

Go to Step 15

Go to Step 22

15

With the test lamp connected to battery positive voltage, probe the door lock actuator lock control circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 25

Go to Step 16

16
  1. Remove the rear door unlock relay.
  2. With the test lamp connected to battery positive voltage, probe the unlock relay ground circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 26

Go to Step 27

17
  1. Remove the rear door unlock relay.
  2. Connect a test lamp to a good ground.
  3. Probe the battery positive voltage circuit (high current) cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 18

Go to Step 27

18

With the test lamp connected to a good ground, probe the unlock relay control circuit cavity in the fuse block.

Does the test lamp illuminate?

Go to Step 23

Go to Step 19

19
  1. Connect a test lamp to battery positive voltage.
  2. Probe the unlock relay control circuit cavity in the fuse block.
  3. Activate a door lock switch to the unlock position.

Does the test lamp illuminate?

Go to Step 20

Go to Step 23

20

With the test lamp connected to battery positive voltage, probe the door lock actuator unlock control circuit cavity in the rear fuse block.

Does the test lamp illuminate?

Go to Step 25

Go to Step 21

21
  1. Remove the rear door lock relay.
  2. With the test lamp connected to battery positive voltage, probe the lock relay ground circuit cavity in the rear fuse block.

Does the test lamp illuminate?

Go to Step 25

Go to Step 27

22

Test for an open short to ground or short to battery in the door lock relay lock control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 33

Go to Step 28

23

Test for an open short to ground or short to battery in the door unlock relay lock control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 33

Go to Step 28

24

Test for a short to ground in the door lock actuator lock and unlock control circuits. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 33

Go to Step 27

25

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

Did you find and correct the condition?

Go to Step 33

Go to Step 29

26

Inspect for poor connections at the rear 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 33

Go to Step 30

27

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

Did you find and correct the condition?

Go to Step 33

Go to Step 31

28

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 33

Go to Step 32

29

Replace the rear door lock relay.

Did you complete the repair?

Go to Step 33

--

30

Replace the rear door unlock relay.

Did you complete the repair?

Go to Step 33

--

31

Replace the rear fuse block.

Did you complete the repair?

Go to Step 33

--

32

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

Did you complete the repair?

Go to Step 33

--

33

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2