GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: The door key cylinder unlock feature is inoperative when unlocking the doors using the door key cylinder.

1

Did you perform the Automatic Door Locks System Check?

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Go to Step 2

Go to Automatic Door Locks System Check

2

Inspect the service parts identification label for RPO UA6. Refer to RPO Code List in General Information.

Is the vehicle equipped with the content theft deterrent (RPO UA6)?

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Go to Step 3

Go to Step 9

3

Did you perform the BCM Diagnostic System Check?

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Go to Step 4

Go to Diagnostic System Check - Body Control System in Body Control System

4

  1. Open the drivers door.
  2. Manually lock the drivers door.
  3. Disconnect the body control module (BCM) connector C2.
  4. Insert a key in the drivers door cylinder lock.
  5. Connect a test light between the B+ and BCM harness connector C2 terminal C5.
  6. Rotate the key to unlock the door while observing the test light.

Does the test light illuminate?

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Go to Step 7

Go to Step 5

5

  1. Disconnect the left drivers door key cylinder lock switch electrical connector.
  2. Connect a test light between the B+ and the key cylinder lock switch harness connector terminal A.

Does the test light illuminate?

--

Go to Step 6

Go to Step 10

6

  1. Connect a digital multimeter (DMM).
  2. Measure the resistance between the key cylinder lock switch harness connector terminal B and the BCM harness connector C2 terminal C5.

Is the resistance less than the specified range?

2 ohms

Go to Step 12

Go to Step 13

7

  1. Remove the key from the left front door.
  2. Open the right front door.
  3. Manually lock the right front door.
  4. Insert the key into the right front door lock cylinder.
  5. Connect a test light between the B+ and the BCM harness connector C2 terminal C5.
  6. Rotate the key to unlock the door while observing the test light.

Does the test light illuminate?

--

Go to Step 14

Go to Step 8

8

  1. Disconnect the passengers right door key cylinder lock switch electrical connector.
  2. Connect a test light between the B+ and the key cylinder lock switch harness connector terminal A.

Does the test light illuminate?

--

Go to Step 6

Go to Step 11

9

The door key cylinder unlock feature is only available on vehicles equipped with the content theft deterrent (RPO UA6).

Is the action complete?

--

Go to Step 15

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10

Repair the poor connection or an open in circuit 750.

Is the repair complete?

--

Go to Step 15

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11

Repair the poor connection in circuit 350.

Is the repair complete?

--

Go to Step 15

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12

Repair the key cylinder lock switch.

Is the repair complete?

--

Go to Step 15

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13

Repair the poor connection or and open in circuit 781.

Is the repair complete?

--

Go to Step 15

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14

  1. Inspect the BCM connector C2 terminal C5 for a poor terminal contact.
  2. If the BCM connector C2 terminal C5 is good, replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

Go to Step 15

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15

  1. Turn the ignition switch to the OFF position.
  2. Reinstall the connectors.
  3. Reinstall the components.
  4. Turn the ignition switch to the RUN position for 6 seconds.
  5. Turn the ignition switch to the OFF position.
  6. Remove the MALL PGM fuse.
  7. Turn the ignition switch to the ACC position. The BCM chimes the same number of times to the BCM type installed in the vehicle.
  8. Within one second, turn the ignition switch from the ACC position to the OFF position then back to the ACC position. The BCM will sound any DTCs that are stored.

Are any BCM DTCs present?

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Go to Diagnostic System Check - Body Control System in Body Control System

Go to Automatic Door Locks System Check