'94 Chevy C1500 Simultaneous Stall/Electrical Malfunction

[mmm98]

I have a 1994 stepside Chevy C1500, 5.7 L V8 engine

 

This past week, my truck has started acting up. Within the first 5-10 minutes of driving, after being at a complete stop at a light or a stop sign, when trying to accelerate, the truck engine along with the inside electrical system dies. Sometimes it’s a barely noticeable skip but sometimes it shuts off enough for the radio to completely turn off and back on again. As far as I can tell, the dash lights, AC control panel, and radio all turn off as well as the engine but for less than a second. This has happened pretty consistently for the past week, but it only happens once or twice within the first 10 or so minutes of driving which makes me think it has something to do with the truck warming up.

 

For the first time today, the speedometer dipped by 20 mph for a second before jumping back up to normal and then a few seconds later, the truck revved up by about 1000 rpms before dropping back down after a second.

 

I’m at a complete loss as to the issue. I’ve checked battery connections and alternator connections. Everything appears fine to me. Does anyone have any guesses?

 

I know that I need to replace the idle air control valve which is on my list of things to do, but I don’t think that’s the issue because I can’t imagine how that would be affecting the electrical components.

Edited May 1, 2022 by mmm98

[richard wysong]

check the wire and connections  from the battery to the underhood fuse box (PDB). if that checks out try doing the wiggle test, wiggle and move the wiring harnesses with it running and see if you  get any reaction. you may want to do voltage drop or resistance tests instead of just visual. it's also possibly a bad ignition switch

[Sven Gonzales]

Check your powers and grounds with test light. Search YouTube for best way.

[thx1138v2]

Coming home from the grocery store I noticed the tach and the speedometer jumping wildly all over the dial. I pulled up in the driveway, let it idle for a bit, and then gunned the engine. Sitting still in the driveway the tach and the speedometer were still both jumping all over as I gunned it. I turned the engine off and there was no electricity to any of the systems in the truck. I measured the battery voltage and it was 12.81V. Further explorations revealed a loose ground cable to the battery terminal although it still looked and felt connected. After removing it I found corrosion on the cable end and the battery side post. Cleaned it all up and replace the terminal bolt and every thing is OK again.

I'm guessing the loose cable was bouncing around on the terminal and causing the tach and speedometer needles to jump wildly as if I had just turned the key to the on position.

 

It could have also been that when sitting in the drive way and gunning the engine, it was torqing on the motor mounts to cause the same problem.

 

Don't know for sure but it's OK now.

 

So check your ground cable first. You might have to split the insulation and look corrosion under the insulation.