GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) controls the following lamps when the instrument panel (I/P) dimmer switch is ON or any door is opened:

    • The I/P courtesy lamp, LH
    • The I/P courtesy lamp, RH
    • The inside rear view mirror lamps
    • The cargo lamp
    • The roof rail reading lamp, LH
    • The roof rail reading lamp, RH
    • The sunshade lighted vanity mirror lamps, LH
    • The sunshade lighted vanity mirror lamps, RH

The BCM monitors all but the sunshade lighted vanity mirror lamps for a short to ground or a short to voltage.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2617 Passenger Compartment Dimming Circuit Low

Conditions for Running the DTC

Voltage supplied to the module is in the normal operating range, approximately 10-16 volts.

Conditions for Setting the DTC

    • The BCM detects a short to ground in the courtesy lamps supply voltage circuit of the interior lamps when the dimmer switch is in the OFF position, and the doors are not open.
    • The condition is present for more than 3 ms.

Action Taken When the DTC Sets

The BCM stores DTC B2617 in memory.

Conditions for Clearing the MIL/DTC

    • A current DTC B2617 clears if the BCM no longer detects a short to ground.
    • A history DTC B2617 clears after 100 consecutive ignition cycles.
    • The BCM receives the Clear Code command from the scan tool.

Diagnostic Aids

    • If the DTC B2617 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections .
    • An intermittent short to ground in the following locations may cause an intermittent malfunction to occur:
       - The courtesy lamps supply voltage circuit
       - The BCM

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Turn the ignition to the RUN position.

Do the interior lamps illuminate with the instrument panel (I/P) dimmer switch in the ON position?

Go to Diagnostic Aids

Go to Step 3

3

  1. Disconnect the body control module (BCM) connector C3.
  2. Connect a test lamp between the supply voltage circuit of the interior lamps at the BCM connector and battery voltage.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

Test for a short to ground in the courtesy lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 6

--

5

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 6

--

6

  1. Use a 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?

System OK

Go to Step 3