GM Service Manual Online
For 1990-2009 cars only

Object Number: 399611  Size: MF
Body Control Module Components

Circuit Description

The body control module (BCM) monitors CKT 195 as an input in order to determine if the door relay circuit is shorted to battery voltage. When CKT 195 is shorted to battery voltage the BCM sets DTC B3138.

Conditions for Setting the DTC

All of the following conditions must be met:

    • When CKT 195 is shorted to battery voltage.
    • The system voltage must be between 9-16 volts.
    • The above conditions must be met for 30 seconds.

Action Taken When the DTC Sets

    • The lock system does not function properly.
    • DTC B3138 stores in BCM memory.

Conditions for Clearing the DTC

    • A current DTC clears after the next fault free ignition cycle.
    • A history DTC clears after 100 consecutive ignition cycles without a fault present.
    • Clear history and current DTCs using a Scan Tool .

Diagnostic Aids

Using J 39200 , compare the scan tool values to the actual BCM values.

Test Description

The numbers below refer to the numbers on the diagnostic table.

  1. This step determines if the door lock relay is operating properly

  2. This step determines a short to battery in CKT 195 within the left IP wiring harness junction block.

  3. This step determines a short to battery in CKT 195 between the left IP wiring harness junction block and the Body Control Module (BCM).

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 Body Control Module (BCM) System Check performed?

--

Go to Step 2

Go to Body Control Module System Check

2

Was the Power Door Locks System Check performed?

--

Go to Step 3

Go to Power Door Locks System Check in Doors

3

Do the door lock actuators operate properly?

--

Go to Step 11

Go to Step 4

4

Replace the door lock relay with a known good relay from the left IP wiring harness junction block.

Do the door lock actuators operate properly?

--

Go to Step 5

Go to Step 6

5

Replace the door lock relay.

Is the repair complete?

--

Go to Step 11

--

6

  1. Disconnect the left IP wiring harness junction block connector C1.
  2. Remove the ignition key from the ignition switch.
  3. Using J 39200 DMM, measure the voltage in CKT 195 between the left IP wiring harness junction block connector C1 terminal F10 and ground.

Does the measured voltage equal the specified value?

0 V

Go to Step 7

Go to Step 8

7

Replace the left IP wiring harness junction block.

Is the repair complete?

--

Go to Step 11

--

8

  1. Disconnect the BCM connector C3.
  2. Using J 39200 DMM, measure the voltage in CKT 195 between the BCM connector C3 terminal A8 and ground.

Is the measured voltage equal to the specified value?

0V

Go to Step 10

Go to Step 9

9

Repair the short to battery in CKT 195 between the BCM connector C3 terminal A8 and the left IP wiring harness junction block. connector C1 terminal F10. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

10

Replace the BCM. Refer to the following procedures:

    • BCM Replacement.

Is the repair complete?

--

Go to Body Control Module System Check

--

11

  1. Clear the DTC from the memory.
  2. Operate the power door locks.

Is the DTC cleared from the memory?

--

Go to Body Control Module System Check

--