2016 gmc Savana 3500 6.0 Cranks but no start - ABS flickering and Brake light

Tylerm4747

2016 gmc Savana 3500 6.0 Cranks but no start - ABS flickering and Brake light. First abs light came on out of no where and truck stalled, wouldn’t start. Fuel pump wasn’t kicking out with key turned or while trying to start (fuel pump 2 months old). Fuel pump relay wasn’t working. Relay tested good and fuse was good. Installed new junction box (fuse box) and truck ran good for 2 days. Today abs light and brake light started coming on and off during the work day and truck died. Won’t start again, relay good and fuse good for fuel pump, fuel pump not running now during turn key or trying to start.

thecardoc3

The first thing to do is to try to pull codes from every module on the car and see what you find. Is there anything else that you notice that isn't working like power seat, windows, wipers?

Tylerm4747

No codes showing other than typical o2 sensors. Everything works great until driven for roughly 30 mins- 2 hours then abs and park brake light with flash and starts stalling the truck. Then truck wont start, let truck sit for 6 plus hours and truck will start again and run for 30 mins - 2 hours.

thecardoc3

All of the testing needs to be done while the truck is acting up. See if you can try pulling codes when it has stalled and won't restart. When it won't restart does the starter crank the engine or not?

thecardoc3

I'm not a fan of "silver bullets" but there is something you could check pretty easily and see if it has failed. Inspect the ground cable between the engine block and the right front frame rail near the engine mount. They often corrode and can cause some of the symptoms as you have described. If it is showing signs of corrosion, replace it even if it doesn't solve the symptom. If you have the vehicle in a failure mode and you want to prove if that ground has failed, just use a jumper cable between the engine and the frame and see if the vehicle then starts.