GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Terraza 🢒 DTC 🢒 DTC B2610

Circuit Description

The body control module (BCM) applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp switch. When the switch is placed to the desired position, the dimmed voltage setting is applied from the interior lamp switch through the I/P dimming control circuit to the BCM. The BCM applies the dimmed voltage to the instrument panel lamp supply voltage circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2610 Passenger Compartment Dimming 1 Circuit

Conditions for Running the DTC
    • The battery voltage must be between 9-16 volts.
    • The ignition in the RUN position.
    • The headlamps into ON position.

Conditions for Setting the DTC
    • When the BCM receives an I/P controls illumination lamp request signal and the I/P dimming voltage reference circuit is shorted to ground, open, or short to battery positive voltage
    • When the BCM is not receiving an instrument panel controls illumination lamp request signal and the I/P dimming control circuit is shorted to battery positive voltage or open

Action Taken When the DTC Sets

The instrument panel illumination lamps and the controls illumination lamps will not operate or are always ON.

Conditions for Clearing the MIL/DTC
    • This DTC will clear on current status after the condition for setting the fault is corrected.
    • 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

Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections .

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 3

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the headlamps in the ON position.
  3. Move the instrument panel (I/P) dimmer switch from full dim to full bright and back to full dim, leaving in each position for 10 seconds.

Do the dimming lamps illuminate as expected?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Disconnect the body control module (BCM) connector C1.
  2. Using a DMM set to the ohms setting, probe between the I/P dimming voltage reference circuit and the I/P dimming control circuit.
  3. Move the I/P switch from full dim to full bright.

Does the DMM reading change values?

Go to Step 7

Go to Step 4

4

Test the I/P lamps dimming voltage reference circuit for the following:

    • An open
    • A high resistance
    • A short to battery positive voltage
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

Test the I/P dimming control circuit for a short to battery positive voltage or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 8

Go to Step 5

6

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 8

--

7

Replace the BCM. Refer to Control Module References 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.

Does the DTC reset?

Go to Step 3

System OK