Has some power but dash lights and right headlight not working and no crank and no start?

MCQUEENSARA1981

MEMBER
2015 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
80,000 MILES

We drove the truck listed above Lt model to the store and came out and went to start the truck and got no dash lights, no crank, no start and no right head light. We also don't even have power to the windows, or driver seat. We had the battery tested and recharged and still nothing. Replaced the terminals and got the same result. We also noticed when the truck is turned to the start position the headlights go off in the dark. Have also checked the ground cables and replaced both positive and negative cables to the battery. And still same result. Checked all fuses and relays and all are good. We also noticed that while we were sitting waiting for a tow the keys were out of the ignition and all of a sudden, the cab lights came on and no one touched them. We have yet to be able to get it to start. What could the issue be?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
47,662 POSTS

It sounds like the BCM, or the ignition switch has gone out. When you said you checked the fuses did you test them for power as well?

Here is a guide to help you check fuse #8 in the main battery fuse block:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

The ignition switch feeds directly into the BCM so please check the fuse DLIS in the fuse panel on the left side of the dash (5 amp). Next, we should do a CAN scan to see what comes up. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is how to change the BCM and ignition switch out in the images below. You can get a preprogrammed unit by searching Google or Ebay. Also, I have a wiring diagram that shows the main power feeds for the truck, please check them for power as well. Check out the images (below). Please let us know what you find. We are interested to see what it is.

Images (Click to make bigger)