Test Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The number(s) below refer to the step number(s) on the diagnostic table.

2) - Listen for an audible click when the ground illumination relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3) - Tests for voltage at the coil side of the ground illumination relay. The SEO1 fuse supplies power to the coil side of the ground illumination relay.
4) - Verifies that the body control module is providing ground to the ground illumination relay.
5) - Tests if ground is constantly being applied to the ground illumination relay.
12) - After replacement of the BCM you must calibrate the new module for proper operation.

Fig 1: DTC B2642 Diagnosis (Steps 1-2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2642 Diagnosis (Steps 3-13)

Courtesy of GENERAL MOTORS CORP.