Vehicle is 99 Suburban K1500 4WD LE. Just recently an electrical problem appeared where the ignition and brake circuits act as if they are connected. For example, turn on the ignition and the brake lights come on. OR - with the ignition off, push on the brake pedal and the dash board and guages come alive just as if the ignition switch was moved to the ON position. Furthermore, if the engine was running but the the ignition switch is moved to the OFF position, then the engine will keep running as long as the brake pedal is held down. Lift up off of the brake pedal and the engine dies. Again, it appears that a cross connection (short) has developed between the brake and ignition circuits. I searched through the dash and center console for a Body Control Module thinking this might be the problem, but could not find the BCM. I read perhaps the BCM is integrated with the Engine Control Module so I (successfully) changed that out but it did not solve the problem. I have also changed the stop light switch. Perhaps a short in a wire bundle or connector somewhere? Any ideas or suggestions where to start? Thanks is advance.

 

I had a problem like that years ago and found the problem to be at the back of the fuse block under the dash. If you have another fuse block under the hood check there as well. The problem was that over time the wires at the backside of the fuse block had rubbed together and the ignition on mine had rubbed the insulation to the headlights and when I pulled to a stop at night and shut off the engine, the engine would not die till I shut off the headlights. Remove attaching screws and pull the fuse block away and look for rubbed thru insulation at back of the fuse block(s).

 

Thanks, Navy. I went digging around in the dash and the problem stopped immediately. I dug through wires around fuse boxes, wire bundles, connectors, etc., in the dash and under the hood, but couldn't really find any that showed external damage or chafing. Tried to separate things as best as I could. The problem has gone away for now and the vehicle is drive-able again, but I'm not going to feel good about this one until I find and fix the culprit. Thanks again for the advice.

 

Glad I could help. You disturbed the problem with what you did. Hopefully it stays gone. I would still recommend looking at the backside of the fuse boxes.

 

The ignition system of a car is a complex circuit of components. ... From there, a wire takes this current over to the distributor.

 

The problem was found to be with the hazard switch on top of the steering column. Replaced the multifunction switch and all appears well. Many thanks to all who assisted with their posts. Be good and stay safe. 🙂

 

Thanks for coming back with what you found.