I pulled the motor in my 07 classic 5.3. Did oil pump (the issue) and all gaskets except head gaskets. Now my truck is acting funny. At first i had 3 trans codes and reduced power, and the truck would not shut off. If you turned key off dash died, but if you hit brake it starts to come on, then off then on off. Ended up pulling left low beam fuse and it fixed it all. Pulling the light it self made it worse.However now my light did not work. With the fuse in not only did i get the codes but my left light was dim and both high/low beams were on.

so anyways pulled fuse, and wired low beam up with a relay, to right low beam. The relay went nuts. I even tried a second one. Flipped on the high beams and truck shut off instantly. Now i figured a body control module, i cracked it open and it looks pristine. I checked all engine grounds, and tried my best to trace the wires. I guess tomorrow the fender is coming off. A test light between neg cable and post leads me to beleive i have a short. And ive been looking at diagrams all day trying to find common links. All the common is the bcm. Pulled the bcm, and the short is still there.

anyone had this happen? I could see a bad bcm or ignition but i had the motor out, so what are the odds? And i got it to work fine, sorta. Im not sure what to do next. Maybe I need to buy a need car I can get a payday loans in MI for the new Silverado.

my buddy, same truck, same oil pump issue, did his in the truck, and is having issues now.

 

This sounds like it may be sneak circuit feedback, meaning certain components cannot find a direct path to ground and are finding ground wherever they can. Given that you recently pulled the engine, I think it’s a strong possibility.

Try making a few jumper wires from 10 or 12 gauge wire - alligator clips on the ends are easiest, but ring terminals will work if you can find bolts that will break loose to attach them. Install them in the following locations, making absolutely certain the contact points are clean so you know there’s good connection:

1) Engine block to frame.
2) Engine block to firewall.
3) Firewall to frame.
3) Lower radiator support to block.

If some or all of the issues disappear, either you forgot to hook up a primary ground or the harness was damaged. Remove the jumper wires 1 at a time to narrow down which ground could be the source (for example, if you remove the lower radiator to block jumper and the issues return, that would indicate problems with ground point G100.