DTC B2618: Passenger Compartment Dimming No. 2 Circuit High: Description

WARNING: This page is about a different car, the 1999 Buick Regal and 1999 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

Body Control Module (BCM) turns on interior lights when one or more of the following occur:

Any door is opened.
Dimmer switch in DOME position.
During exit or delayed illumination functions.
When left or right front outside door handles are lifted, whether locked or unlocked.
Locking or unlocking doors with remote transmitter.

BCM uses power from circuit No. 240 (Orange wire) through BCM and circuit No. 1732 (Orange wire) to power courtesy (interior) lights.

All doors contain door lock ajar switch. When driver's door is open, door lock ajar switch closes and sends a ground signal is sent along circuit No. 49 (Dark Blue wire) to BCM to turn interior lights on. When LF, RF, LR or RR door are opened, corresponding door lock ajar switch closes and sends ground signal along circuit No. 727 (Dark Blue/White wire) to turn interior lights on.

When either LF or RF door handle is lifted, corresponding door lock switch sends ground signal to BCM along circuit No. 727 (Dark Blue wire). Rear doors do not have this function. BCM will ground circuit No. 157 (Gray wire) when circuits No. 727 or 49 are grounded.

BCM will turn off interior lights when all doors are closed and dimmer switch is not in DOME position. When doors are closed, circuits No. 727 (Dark Blue/White wire) and 49 (Dark Blue wire) are open. BCM receives signal and opens circuit No. 157 (Gray wire) turning interior lights off.

BCM will set DTC B2618 if BCM detects a short to voltage in circuit No. 157 (Gray wire) for longer than 0.15 seconds.

If conditions for malfunction no longer exist, history DTC will clear after 100 consecutive ignition cycles. DTC B2603 will also clear when conditions no longer exist or scan tool is used to clear codes.

NOTE: If DTC B2618 is a history code, problem may be intermittent. Wiggle wires while performing the following test.

NOTE: When ignition switch is turned to RUN position with BCM disconnected, PCM-related DTC P1626 will be set. After BCM repair is completed, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.