DTC B2602: DRL Control Module Circuit (Short To Ground Or Open): 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) interfaces with Daytime Running Light (DRL) control module to allow BCM to determine current ambient light operation mode. BCM uses class 2 serial data line to communicate this information to Instrument Panel Cluster (IPC). BCM uses information from circuit No. 1970 (Pink/White wire) to energize headlights for twilight sentinel feature.

DTC B2602 will set when BCM detects a short to ground or open in circuit No. 1970 (Pink/White wire) when ignition switch is turned from START to RUN position. No driver warning message will be displayed.

When ignition switch is turned from OFF to RUN position, a current DTC is always cleared. If condition for malfunction is still present, DTC will reset as a current DTC. If condition for malfunction no longer exists, history DTC will clear after 100 consecutive ignition cycles. DTC B2602 will also clear when conditions no longer exist or scan tool is used to clear codes.

NOTE: If DTC B2602 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.