GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2006 🢒 I-280 🢒 Brakes 🢒 Park Brake 🢒 DTC B3142 or B3143

Circuit Description

The body control module (BCM) provides an output to the driver switch assembly through the door unlock control circuit for controlling automatic door unlock, anti-lockout, and keyless entry unlock functions.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B3142 Unlock Switch Circuit Low
    • DTC B3143 Unlock Switch Circuit High

Conditions for Setting the DTC
    • The BCM detects a short to ground on the door unlock control circuit for greater than 60 seconds.
    • The BCM detects a short to battery on the door unlock control circuit for greater than 1 second.

Action Taken When the DTC Sets
    • The BCM stores DTC B3142 or B3143 in memory.
    • The BCM will disable the output and all operations of the output until the fault no longer exists.

Conditions for Clearing the DTC
    • The BCM no longer detects the short to ground on the door unlock control circuit for greater than 60 seconds.
    • The BCM no longer detects the short to battery on the door unlock control circuit for greater than 1 second.
    • 100 consecutive ignition cycles have been recorded without the DTC being detected.

Diagnostic Aids

If DTC B3142 or B3143 are history DTCs, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step determines whether the driver switch assembly is stuck or shorted.

Step

Action

Yes

No

Schematic Reference: Door Lock/Indicator Schematics

Connector End View Reference: Power Door Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn OFF the ignition.
  2. Disconnect the driver switch assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool in order to clear the DTCs.
  5. Operate the vehicle within normal operating conditions.

Does the DTC reset?

Go to Step 3

Go to Step 4

3

Test the door unlock control circuit for a short to ground or voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 5

4

Inspect for poor connections at the harness connector of the driver switch assembly. 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 8

Go to Step 6

5

Inspect for poor connections at the harness connector of the body control module (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 8

Go to Step 7

6

Replace the driver switch assembly. Refer to Door Lock and Side Window and Outside Rearview Mirror Remote Control Switch Replacement .

Did you complete the replacement?

Go to Step 8

--

7

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 8

--

8
  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