GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Did you perform the Door Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Door Systems

2

  1. Turn the ignition off, key out.
  2. Operate the driver door lock switch.
  3. Operate the passenger door lock switch.

Do both door locks and switches operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Are the door locks totally inoperative?

Go to Step 5

Go to Step 4

4

Does either door lock actuator operate properly from BOTH switches?

Go to Step 16

Go to Step 11

5

Connect a test lamp between the battery positive voltage circuit of the body control module (BCM) at the BCM connector C2 terminal B and ground. Refer to Circuit Testing in Wiring Systems.

Did the test lamp illuminate?

Go to Step 6

Go to Step 7

6

  1. Disconnect the driver door lock switch. Refer to Door Lock Switch Replacement .
  2. Test the ground circuit at the switch by connecting a test lamp between the battery positive voltage circuit (B+) and the ground circuit of the door lock switch connector.
  3. Test the ground circuits at the BCM connector C2 pin A and connector C3 pin C1 in the same way.

Does the test lamp illuminate in each case?

Go to Step 9

Go to Step 12

7

Test the battery positive voltage circuit to the BCM for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 8

8

  1. Ensure the COURTESY Fuse 8 20A is good.
  2. Operate the driver door lock switch to the lock and unlock positions.

Did the COURTESY Fuse open?

Go to Step 17

Go to Step 21

9

  1. Reconnect the driver door lock switch.
  2. Connect a test lamp between BCM connector C1 terminal B and ground. Refer to Circuit Testing in Wiring Systems.
  3. While observing the test lamp, move the driver door lock switch to the lock position.

Does the test lamp illuminate?

Go to Step 10

Go to Step 17

10

Test for an open in the door lock actuator lock control circuit between the BCM connector C1 terminal B and S504. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 21

11

  1. Disconnect the inoperative door lock switch. Refer to Door Lock Switch Replacement .
  2. Test the ground circuit at the inoperative switch by connecting a test lamp between the battery positive voltage circuit (B+) and the ground circuit of the door lock switch connector.

Does the test lamp illuminate?

Go to Step 13

Go to Step 12

12

Repair the open you found in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 25

--

13

Individually test each suspect door lock switch while removed by connecting a DMM between switch terminal A and terminal C then D while actuating the switch to lock and unlock, respectively.

Does the DMM indicate continuity when the switch is depressed and infinity when released in each case?

Go to Step 14

Go to Step 19

14

  1. Reconnect the door lock switch(es).
  2. Using a test lamp connected to B+, probe the lock and unlock switch circuits at the BCM. Refer to Circuit Testing in Wiring Systems.
  3. While observing the test lamp, move the driver door lock switch to the lock and unlock position corresponding to the circuit being tested.
  4. Repeat for the passenger door lock switch.

Does the test lamp illuminate in each case only while the switch is depressed?

Go to Step 15

Go to Step 18

15

  1. Using a test lamp connected to ground, probe the lock and unlock actuator circuits at the BCM connector. Refer to Circuit Testing in Wiring Systems.
  2. While observing the test lamp, move the driver door lock switch to the lock and unlock position to test each respective circuit.

Does the test lamp flash in each case only when commanded?

Go to Step 16

--

16

  1. Disconnect the suspect door lock actuator.
  2. Using a test lamp connected to ground, probe the lock and unlock circuits at the actuator connector. Refer to Circuit Testing in Wiring Systems.
  3. While observing the test lamp, move the driver door lock switch to the lock and unlock position to test each respective circuit.

Does the test lamp flash in each case only when commanded?

Go to Step 23

Go to Step 17

17

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

Did you find and correct the condition?

Go to Step 25

Go to Step 23

18

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

Did you find and correct the condition?

Go to Step 25

--

19

Inspect for poor connections at the inoperative door lock switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 20

20

Replace the inoperative door lock switch. Refer to Door Lock Switch Replacement .

Did you complete the repair?

Go to Step 25

--

21

Inspect for poor connections at the Body Control Module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 22

22

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the repair?

Go to Step 25

--

23

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

Did you find and correct the condition?

Go to Step 25

Go to Step 24

24

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

Did you complete the repair?

Go to Step 25

--

25

  1. Replace the COURTESY Fuse 8 20A if necessary.
  2. Operate the system in order to verify the repair. If the fuse opens, go to Step 17.

Did you correct the condition?

System OK

Go to Step 2