Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC 21/31: Courtesy Lights Feed (Circuit Shorted To Ground): Description
BCM provides a 12-volt input to courtesy lights on courtesy lights feed circuit when commanded by instrument panel dimmer switch, left or right 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, faulty harness or connector, courtesy lights feed circuit is shorted 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 illuminate 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.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.