GM Service Manual Online
For 1990-2009 cars only

For a full page schematic, refer to Door Lock/Indicator Schematics

Circuit Description

The body control module (BCM) monitors and supplies an output voltage on CKT 195 to lock the doors. When the BCM receives a lock signal from the remote control door lock receiver the BCM supplies voltage to the lock relay to lock the doors.

Conditions for Running the DTC

    • The system voltage must be between 9.0 and 16.0 volts.
    • The key fob and or door locks must be activated to lock/unlock the doors.

Conditions for Setting the DTC

    • When CKT 195 is shorted to battery voltage for approximately 3 minutes.
    • The system voltage must be between 9.0-16.0 volts.

Action Taken When the DTC Sets

The power door lock system will not function with the remote keyless entry system or either power door lock switches.

Conditions for Clearing the MIL/DTC

    • A current DTC will clear immediately after the short to battery voltage is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTC(s) can be cleared using a scan tool.

Diagnostic Aids

    • Always begin diagnosis with the first DTC listed on the scan tool.
    • The scan tool must display DTC B3138 as a current code before performing these diagnostics.
    • Perform a visual inspection for loose or poor connections at all related components
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Listen for an audible click when the door lock relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

  2. Verifies that the Body Control Module (BCM) is providing voltage to the door lock relay.

  3. Tests for an open in the ground circuit to the door lock relay.

  4. Tests if voltage is constantly being applied to the door lock relay.

  5. After replacement of the BCM you must calibrate the new module for proper operation.

Step

Action

Value(s)

Yes

No

1

Did you perform the Power Door Systems Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Power Door Systems .

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the door lock relay ON and OFF.

Does the door lock relay turn ON and OFF with each command?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the door lock relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the door lock relay with a test lamp connected to a good ground.
  5. With a scan tool, command the door lock relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

--

Go to Step 4

Go to Step 5

4

  1. Connect a test lamp between the control circuit of the door lock relay and the ground circuit of the door lock relay .
  2. With a scan tool, command the door lock relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

--

Go to Step 8

Go to Step 10

5

Does the test lamp remain illuminated with each command?

--

Go to Step 7

Go to Step 6

6

Test the control circuit of the door lock relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7

Test the control circuit of the door lock relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

8

Inspect for poor connections at the door lock relay . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

Repair the ground circuit of the door lock relay . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

11

Replace the door lock relay .

Did you complete the replacement?

--

Go to Step 13

--

12

  1. Replace the BCM. Refer to Body Control Module Replacement in Body Control System.
  2. Program the BCM with the proper calibrations. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.
  3. Perform the learn procedure.

Did you complete the replacement?

--

Go to Step 13

--

13

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK