GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: The LOCK and UNLOCK functions of the automatic are inoperative when using the door lock switches, the key cylinder lock switch or the keyless entry transmitter. The automatic door lock features are all inoperative.

1

Was the BCM diagnostic system check performed?

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Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Remove the PWR LOCK fuse.
  2. Inspect the PWR LOCK fuse.

Is the PWR LOCK fuse open?

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Go to Step 3

Go to Step 4

3

  1. Replace the PWR LOCK fuse.
  2. Press lock, then unlock on either door lock switch.
  3. Remove the PWR LOCK fuse.
  4. Inspect the PWR LOCK fuse.

Is the PWR LOCK fuse open?

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Go to Step 6

Go to Step 4

4

Backprobe between the BCM connector C1 terminal H and ground.

Does the test lamp light?

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Go to Step 5

Go to Step 11

5

  1. Manually lock all of the vehicle doors.
  2. Disconnect the BCM connector C1.
  3. Connect a 25A fused jumper between the BCM harness connector C1 terminal C and ground.
  4. Momentarily connect a jumper between B+ and the BCM harness connector C1 terminal A, while observing the driver door lock.
  5. Momentarily connect a jumper between B+ and the BCM harness connector C1 terminal B, while observing the passenger door lock(s).

Do all of the vehicle doors unlock?

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Go to Step 10

Go to Step 11

6

  1. Disconnect the BCM connector C1.
  2. Connect between B+ and the BCM connector C1 terminal H.

Does the test lamp light?

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Go to Step 12

Go to Step 7

7

Connect a test lamp between B+ and the BCM connector C1 terminal C.

Does the test lamp light?

--

Go to Step 13

Go to Step 8

8

Connect a test lamp between the BCM connector C1 terminal C and ground.

Does the test lamp light?

--

Go to Step 14

Go to Step 10

9

Repair the poor connection or open in circuit 1540.

Is the repair complete?

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Go to Step 15

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10

  1. Inspect the BCM connector C1 terminal E for a poor terminal contact. Repair the terminal as needed.
  2. If the BCM connector C1 terminal E is OK, replace the BCM. Refer to Body Control Module Replacement in Body Control Systems.

Is the repair complete?

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Go to Step 15

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11

Repair a short to ground in circuit 1540.

Is the repair complete?

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Go to Step 15

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12

Repair a short to ground in circuit 1540.

Is the repair complete?

--

Go to Step 15

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13

Repair a short to ground in circuit 294 and/or circuit 295.

Is the repair complete?

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Go to Step 15

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14

Repair a short to B+ in circuit 294 and/or circuit 295.

Is the repair complete?

--

Go to Step 15

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15

  1. Turn the ignition switch to the LOCK position.
  2. Re-install the connectors/components that were removed.
  3. Turn the ignition switch to the RUN position for 6 seconds.
  4. Turn the ignition switch to the LOCK position.
  5. Remove the BCM PRGRM fuse.
  6. Turn the ignition switch to the ACC position. (The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle).
  7. Turn the ignition switch from the ACC position, to the LOCK position and back to the ACC position within 1 second. (The BCM sounds any DTCs stored).

Are there any BCM DTCs present?

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Go to Diagnostic System Check - Body Control System

Go to Automatic Door Locks System Check