DTC 21/31: Courtesy Lights Feed Circuit Short To Ground: Description

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.

Body Control Module (BCM) provides a 12-volt input to courtesy lights on courtesy lights feed circuit (Dark Blue/White wire) when commanded by instrument panel dimmer switch, door jamb switch or rear compartment lid ajar indicator switch inputs.

DTC 21 will set when battery circuit is open due to a problem with COURTESY fuse No. 8 (20-amp), faulty harness or connector, courtesy lights feed circuit (Dark Blue/White wire) is short to ground for more than 50 milliseconds while BCM is providing input on circuit, or BCM is defective.

When DTC 21 is set, courtesy lights will not come on and instrument panel dimmer switch will not operate. Glove box and center console lights will also be inoperative. DTC 21 will clear when fault is corrected and memory is cleared.