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 194. When the BCM receives an unlock command from the remote control door lock receiver the BCM supplies voltage on circuit 194 to unlock the passenger door.

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 the BCM receives an unlock signal to unlock the passenger door from the remote control door lock receiver module and circuit 194 is shorted to ground.
    • The system voltage must be between 9.0 volts and 16.0 volts.
    • The above conditions must be met for 0.25 seconds.

Action Taken When the DTC Sets

    • The door lock system will not unlock the passenger door from the key fob.
    • The door lock switches will not lock or unlock the doors.

Conditions for Clearing the MIL/DTC

    • A current DTC will clear after the next fault free passenger door unlock cycle.
    • 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 B3147 as a current code before performing these diagnostics.
    • Perform a visual check for loose or poor connections at all related components
    • Refer to Testing for Intermittent Conditions and Poor Connections

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 Unlock 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 unlock relay.

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

  4. Tests if voltage is constantly being applied to the door unlock 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 unlock relay ON and OFF.

Does the door unock 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 unlock relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the door unlock relay with a test lamp connected to a good ground.
  5. With a scan tool, command the door unlock 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 unlock relay and the ground circuit of the door unlock relay .
  2. With a scan tool, command the door unlock 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 unlock 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 unlock 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 unlock 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 unlock relay . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

11

Replace the door unlock 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