SasquatchNurph

Hi everyone! New guy with first post here. I'm hoping for some help/insight. Sorry for the incoming long post, but I have to detail what happened & what I did to test/troubleshoot.

I own a 2010 Suburban 2500 4WD that lived a hard, former life as an FBI vehicle. No, no lights/siren included. Anyway, I was driving it up the interstate at around 75mph when the following happened in rapid succession:

- A/C went from blowing cold to ambient tempurature
- Radio (aftermarket with Apple play) went black
- ALL needles went to zero
- "Christmas light" show on the dash

Then, everything came back & went out intermittently. We were still doing 75mph with the cruise set. Phone charging (using it for navigation & speedometer) just fine. We planned to stop at a rest area about 15 miles up the road. Limped into there okay. Truck was running as normal. Family went to the restroom & I stayed with the truck to keep it running. Something told me to turn it off, so I did. It never turned back on.

Fast forward to getting it home after a logistical fiasco. Pulled the battery, alternator, & starter to have them tested at my local auto parts store. They all tested "GOOD". Battery voltage was 12.64V with 745CCA (out of a possible 730CCA). I don't know what the output of the alternator was because their machine didn't say that. Just that it was "GOOD". In the process of troubleshooting I tested every fuse & relay that had anything to do with "power", "starter", "run", & the 175A mega fuse. ALL tested perfectly fine.

Then ONLY thing I did was clean the battery terminals & connectors & changed the serpentine belt. I also changed the oil thinking there might have been a hydro lock situation. I was hoping for no "milkshake" in the oil pan & was pleasantly surprised to see BLACK oil come out.

So, I put all parts back in the truck. I opened the door to see the dome light on (it wouldn't do that at the rest stop). Put the key in the ignition & turned it "On". Dash lit up like it was supposed to. Cranked the truck & it fired right up! After a lot of laughter (what else are you going to do in that situation?) & head shaking I just sat there. I let it run for about 15-20 minutes & it ran just fine. Turned it off expecting it to not crank again & it fired right up. So, I took it off the jack stands & turned it around in the driveway so I could take our spare truck to work Monday morning since I have ZERO trust that the Suburban won't leave me stranded again.

The only other thing I want to do is change the grounding strap that goes from the back of the block to the firewall. It's supposed to be silver, but is green right now. If I can remove/clean it that will work. But changing it is an option as well. Any other ideas/insight will be GREATLY appreciated! I'm still leaning towards the alternator &/or battery being the issue. 12.64V & higher CCAs than listed seems fishy to me.

Again, this lived it's former life with the FBI & we know the government doesn't take care of their stuff like they should. So, let me know what the collective thinks.

Thanks!

jfmorris

One thing that isn't clear - when you say "it wouldn't turn back on" at the rest stop - was it turning over at all, or attempting to crank, or was there just nothing when you turned the key?

As far as everything magically working again... you reset the computers in the vehicle with the battery out... I would check wiring harness connectors, fuses, relays, etc, just to make sure everything looks solid.

I recently got stranded with my 1996 C1500, and had to have it towed home on a flat bed. It was the starter, and wouldn't turn over at all. I took the starter to Autozone and they tested it as good. I told them to give me a new one anyway, and boom! Vehicle cranking again. I don't fully trust the kids that were working at Autozone that day to know what they are doing with that tester, and feel that the starter solenoid was bad or intermittent. Sometimes you can beat on a failing starter and get it to crank again, as the vibration frees things up. The tow truck driver was doing that under my vehicle the day I had to get it carried back home...

SasquatchNurph

What I mean is it wouldn't do anything. It was just a giant paperweight. No dome light, dash lights were going crazy, & there was no clicking from under the hood.

Yeah, that's what I'm thinking happened & why I'm in the "honeymoon phase". I have started it in the driveway, but haven't taken it anywhere. I'm honestly afraid of getting stranded again until I figure this issue out.

I agree about the employees at the local auto parts store. I had to show the guy which cable to use to hook up the alternator to test it. SMH I'm thinking it's still the alternator. Although, I'm going to change out as many grounding cables/straps as I can find. The one main one from the block to the firewall is green with corrosion. I'll start there & work my way down.

Thanks for the reply!

jfmorris

Good luck! I hope you get to the bottom of it. Bad/intermittent grounds are certainly a cause of these type issues.

SasquatchNurph

Hi folks! Wanted to provide an update. I changed the ground strap that goes from the firewall to the back of the block. I made a new one out of 10ga wire. The truck still fire right up & runs fine. I took it up to the local auto parts store because they told me they had a scanner. Well, there's was not impressive at all. The one I own is twice as big as theirs & provides more modes/options to scan. So, I plugged mine in & ran it again. No powertrain issues popped, but a ton of exhaust ones did. Nothing I can pinpoint as they were all "little red dots" at the top of the screen. I'll dig more into those.

On a positive note, the A/C seems to have fixed itself. Driving home the 5 minutes from the store it went from blowing ONLY out of the defrost to where ever I told it to. I'm at a loss guys! This one has me scratching my head!!!