GM Service Manual Online
For 1990-2009 cars only

Object Number: 397053  Size: SF
Body Control Module Components
Body Control System Schematics

Circuit Description

CKT 187 is an input to the BCM. The BCM monitors CKT 187 in order to determine if the rear fog lamp circuit is shorted to ground.

Conditions for Setting the DTC

    • There is a short to CKT 187.
    • The system voltage is between 9.0 volts and 16.0 volts.
    • The above conditions exist for 184 seconds.

Action Taken When the DTC Sets

    • The immobilizer PIN will be inactive.
    • The rear fog lamps will not change state when the following actions occur:
       - The park lamps are turned ON.
       - The rear fog lamp switch is pressed.

Conditions for Clearing the MIL/DTC

    • A current DTC will clear after the next ignition cycle that does not contain a fault.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTCs can be cleared using a scan tool.

Diagnostic Aids

    • Always diagnose the first DTC that is listed on the scan tool.
    • Verify that the scan tool displays DTC B2537 as a current code before you perform diagnostics.
    • Inspect the rear fog lamp switch in order to determine if the switch sticks in the ON position.
    • Inspect for loose or poor connections at all of the related components.
    • Refer to Wiring Systems for intermittent and poor connections.

Test Description

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

  1. This step tests the circuit for a short to ground.

  2. This step tests the rear fog lamp switch for a short.

Step

Action

Value(s)

Yes

No

1

Was the BCM Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Disconnect the BCM connector (PPL).
  2. Disconnect the front fog lamp switch connector.
  3. Measure the resistance between the BCM connector (PPL) terminal B7 and ground.

Does the J 39200 digital multimeter (DMM) display the specified value?

OL

(infinite)

Go to Step 3

Go to Step 6

3

Do not depress the fog lamp switch button.

Measure the resistance between the rear fog lamp switch terminal A and terminal B.

Does the J 39200 DMM display the specified value?

OL

(infinite)

Go to Step 4

Go to Step 7

4

  1. Clear the DTCs.
  2. Turn the ignition to the OFF position for 10 seconds.
  3. Turn the ignition to the RUN position for 3.5 minutes.

Does DTC B2537 set as a current code?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Replace the BCM.
  2. Program the correct calibrations into the BCM.
  3. Perform the learn procedure.

Is the repair complete?

--

Go to Step 8

--

6

Repair the short to ground in CKT 187.

Is the repair complete?

--

Go to Step 8

--

7

Replace the rear fog lamp switch.

Is the repair complete?

--

Go to Step 8

--

8

Clear the DTCs.

Is the repair complete?

--

Go to Diagnostic System Check - Body Control System

--