GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Was the system check performed?

--

Go to Step 2

Go to Power Door Locks System Check

2

Perform the body control module (BCM) diagnostic system check.

Are any door lock DTCs present?

--

Go to Body Control Module System Check

Go to Step 3

3

  1. Connect a test lamp to ground.
  2. Backprobe the left IP junction block connector C3 terminal C2.
  3. Activate the door lock switch to the UNLOCK position.

Does the test lamp light?

--

Go to Power Door Locks System Check

Go to Step 4

4

  1. Connect a scan tool to the data link connector (DLC).
  2. Monitor the drivers door unlock relay output while activating the door lock switch to the unlock position.

Does the output change from OFF to ON?

--

Go to Step 6

Go to Step 5

5

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

Is the repair complete?

--

Go to Power Door Locks System Check

--

6

  1. Connect a test lamp to ground.
  2. Backprobe the BCM connector C3 terminal A2.
  3. Activate the door lock switch to the UNLOCK position.

Does the test lamp light?

--

Go to Step 8

Go to Step 7

7

  1. Inspect for a poor connection at the BCM connector C3.
  2. Replace the BCM if there is no poor connection at the BCM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

Go to Power Door Locks System Check

--

8

  1. Remove the driver unlock relay.
  2. Connect a test lamp to ground and J 35616 .
  3. Frontprobe CKT 356 at the left IP junction block.
  4. Activate the door lock switch to the UNLOCK position.

Does the test lamp light?

--

Go to Step 10

Go to Step 9

9

Repair the open or high resistance in CKT 356 between the BCM and the left IP junction block unlock relay terminal 85.

Is the repair complete?

--

Go to Power Door Locks System Check

--

10

Use J 39200 in order to measure resistance between the unlock relay terminal 86 (CKT 150) and ground.

Does the measured resistance equal the specified value?

<1 ohms

Go to Step 11

Go to Step 12

11

Replace the driver unlock relay.

Is the repair complete?

--

Go to Power Door Locks System Check

--

12

Replace the left IP junction block.

Is the repair complete?

--

Go to Power Door Locks System Check

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