GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the BCM diagnostic system check ?

--

Go to Step 2

Go to A Diagnostic System Check - Body Control System

2

Perform the BCM Input/Output test:

  1. Turn off the IP dimmer switch.
  2. Turn the ignition switch to the LOCK position.
  3. Remove the BCM PRGRM fuse.
  4. Turn the ignition switch to the ACC position. The BCM sounds 4 chimes, indicating the BCM type installed on the vehicle.
  5. Within 1 second, turn the ignition switch from the ACC position to the LOCK position and back to the ACC position.
  6. The BCM sounds any stored DTCs.

  7. Turn the IP dimmer switch to the DOME position.
  8. The BCM enters the Input/Output test.

  9. Cycle the IP dimmer switch from the DOME position to the OFF position and back to the DOME position in order to move to the next test.
  10. The BCM runs the Input/Output test in numerical order.

    The BCM flashes the fasten belts indicator and sounds the chime a number equivalent to the Input/Output test number:

    • Test 1 de-energizes CKT 1393 (protected courtesy light output).
    • Test 2 energizes CKT 1393.
    • Test 3 grounds CKT 690 (courtesy lights control).
    • Test 4 turns on the exterior lights.
    • Test 5 sounds the horn relay for 25 ms.
    • Test 6 turns on the security indicator lamp.
    • Test 7 turns off the theft security indicator lamp.

Does the security indicator lamp turn on during test 6?

--

Go to Step 8

Go to Step 3

3

  1. Disconnect the security indicator lamp electrical connector.
  2. Use a test lamp in order to connect between the security indicator lamp connector terminal B and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 9

4

Use a DMM on the DIODE scale in order to connect the red (+) and black (-) probes to terminal B and terminal A of the security indicator lamp respectively.

Does the test lamp light?

--

Go to Step 5

Go to Step 10

5

  1. Disconnect the BCM connector C2.
  2. Use a DMM in order to measure the voltage between the BCM harness connector C2 terminal D15 and ground.

Is the voltage less than the specified value?

2V

Go to Step 6

Go to Step 11

6

Use a DMM in order to measure the resistance between the BCM harness connector C2 terminal D15 and ground.

Is the resistance less than the specified value?

Infinite

Go to Step 7

Go to Step 12

7

Use a DMM in order to connect between the BCM harness connector C2 terminal D15 and the security lamp harness connector terminal A.

Is the resistance measured less than the specified value?

2 ohms

Go to Step 8

Go to Step 13

8

Perform the Content Theft Deterrent System Check again. Refer to Content Theft Deterrent (CTD) System Check.

Does the theft deterrent indicator lamp operate correctly?

--

Go to Step 14

Go to Step 15

9

Repair the following conditions in CKT 640:

    • A poor connection
    • An open

Is the repair complete?

--

Go to Step 16

--

10

Replace the security indicator lamp.

Is the repair complete?

--

Go to Step 16

--

11

Repair the short to B+ in CKT 749.

Is the repair complete?

--

Go to Step 16

--

12

Repair the short to ground in CKT 749.

Is the repair complete?

--

Go to Step 16

13

Repair the following conditions in CKT 749:

    • A poor connection
    • An open

Is the repair complete?

--

Go to Step 16

--

14

A malfunction is not present at this time. Refer to Content Theft Deterrent (CTD) Circuit Description

Is the action complete?

--

Go to Step 16

--

15

  1. Inspect BCM connector C2 terminal D15 for poor terminal contact.
  2. Repair the terminal as needed.

  3. Inspect the security indicator lamp connector terminal A and terminal B for poor terminal contact.
  4. Repair the terminal as needed.

  5. If the connector terminals are not faulty, replace the BCM. Refer toBody Control Module Replacement

Is the repair complete?

--

Go to Step 16

--

16

  1. Turn the ignition switch to the LOCK position.
  2. Reconnect all of the connectors.
  3. Reinstall any components that you removed.
  4. Turn the ignition switch to the RUN position for 6 seconds.
  5. Turn the ignition switch to the LOCK position.
  6. Remove the BCM PRGRM fuse.
  7. Turn the ignition switch to the ACC position. The BCM flashes the fasten belts indicator and sounds the chime 4 times. This identifies the BCM type installed on the vehicle.
  8. Within 1 second, turn the ignition switch from the ACC position to the OFF position and back to the ACC position.
  9. The BCM sounds any stored DTCs.

Are there any BCM DTCs present?

--

Go to A Diagnostic System Check - Body Control System

Go to Content Theft Deterrent (CTD) System Check