1995 Chevy Cheyenne C2500 dies when brake pedal is pressed. Run fine when started. I changed the brake booster and the EGR valve and problem still there!!!!
Many GM vehicles use a wiring grounding buss that the electric fuel pump, brake lights, taillights and back-up lights all share. The buss is a strip connector about 3 inches long and is located in the trunk on the left side down in the well behind the taillight assembly on some cars. You will have to remove the material insulation to get at it. Take the buss connector apart and clean all the connections thoroughly. My 1993 Saturn SC1 engine quit when the brake pedal was pushed because the brake light bulbs were competing with the fuel pump for a good ground and the fuel pump lost out.
My ground buss strip was completely corroded. I had to clean it on a power wire wheel and then use a jewelers file on each female connector after I released them one by one from the buss strip. I also used DeoxIT D5 on the buss before I put it back together. To ensure a good ground I drilled out the copper buss strip and added a 2nd ground wire with a machine screw and connected it to one of the bumper bolts after checking for a good ground. Make sure you use a wire brush or wire wheel on a cordless drill to get to bare metal on the bolt threads and nut. I added a second ground because I did not know how good the factory ground was and I did not want to crawl under the car and try to find it.
After you clean up the ground buss strip, and the car/truck is running great again, open the engine hood and clean up any grounds you can get to. You will be surprised to see how corrosion has built up over the years. Don't forget the DeoxIT D5. The stuff is amazing.