Electrical gremlin

[kfrosty]

My 2 man, I had a starter go bad. Or that's what I think. One day it just wouldn't start and with power getting to the hot switch on the solenoid. Replaced with new starter and things worked fine.

I replaced glow plugs, installed a S3 controller, matching TSU, installed the octopus grounding harness.

The other night, I was going around the property when all of a sudden the headlights started flickering. Then shortly after, there was smoke. I had a flashlight and it came from under the drivers side dash.

I had outside lights, dash lights and heater fan running. Fearing a fire, I shut everything electrical off and the engine. Opened the hood and didn't see anything. So I started it back up and only turned on the headlights. Road around for another 30 minutes.

No issues.

Yesterday, I went out and took the instrument panel out and started looking for a scorched wire. I've looked under the hood and have found nothing.

So I went to start it and the wait light wouldn't come on. Just flash one time and it was a little hard to start as it was 40 degrees.

When it started I noticed the volt meter indicated the alt wasn't charging either. The alternator I suspect had bad diodes as I can see a draw on the batteries with everything off and only when the charge wire from the starter to the alt is connected.

The guy who sold me the alt got me another one. I installed it today. Wait light comes back on now, volt meter after running a 30 seconds or so is showing a charge again.

The thing that worries me is the smoke came from the dash I think as nothing came out when I opened up the hood the night of the problem.

Everything appears to be working now but it worries me that I may have not figured out what the problem actually is. WIth the new alt on, I turned on outside and interior lights, turned on the heater and no issues.

Again I can find no wires with soot on them or see any arc on any metal and the smoke was so bad I would have thought there had to be something.

Thus, curious as to if anybody else has had an issue like this and if you ever figured it out.

Thanks

 

[Retiredwarhorses]

When these wire burn up, they Grenade internally, they can look fine on the outside unless burnt really bad, it take a good cooking before the insulation melts away and exposes any bare wire. The way to tell is to see if the insulation is really soft.
the other problem is of the wire burnt in a sealed bundle, you will never see it.
i had this happen on an M923, I found the wire right afterwards, it was hot and the insulation was goo and soft.
never had an issue after I replaced the switch that caused it. But man...it poured out smoke.

i am NO fan of the 60amp gen unless it's NOS in the box...period. I have had nothing but issues with rebuilds...so I won't touch them. Heck, I used to get them from my OMS shop and they were DOA.
i highly suggest the 200amp upgrade, it just makes it cleaner and easier to service...IMO.
the 200amps have come way down in price.

 

[kfrosty]

RWH,

I have upgraded to a 200 amp. The first one I noticed was causing a draw on the battery when the truck was off. I was told it was a bad diode. So I put on a different this afternoon as mentioned above and still have the draw on the battery with the switch off. I'm starting to think these 200 amp alt for some reason have a small draw unless I just happen to get 2 bad ones.

We'll after the fact how would you suggest finding the source? As of now, the gauges work, heater switch works. I went around the property again today trying to bounce around and find the problem in the daylight.

 

[Stein12501]

Kfrosty I've not let any smoke out of mine yet. I did the 200 amp upgrade and I have the same draw with the switch off. I pulled the regulator and did not have the draw. They sent me another regulator and it still has a small draw. I thought is was the diodes bad, but after reading your problem I'm starting to think like you that the draw might be inherent. I installed a battery disconnect switch so it hasn't been a problem. I have noticed if I run it for a while and charge the batteries the draw is not as bad. As simple as the hmmwv electrical system is it sure is a PITA. I will let you know if I come up with anything. Good Luck

 

[kfrosty]

Kfrosty I've not let any smoke out of mine yet. I did the 200 amp upgrade and I have the same draw with the switch off. I pulled the regulator and did not have the draw. They sent me another regulator and it still has a small draw. I thought is was the diodes bad, but after reading your problem I'm starting to think like you that the draw might be inherent. I installed a battery disconnect switch so it hasn't been a problem. I have noticed if I run it for a while and charge the batteries the draw is not as bad. As simple as the hmmwv electrical system is it sure is a PITA. I will let you know if I come up with anything. Good Luck

Thanks.

Now make that 3. I'm going through one of my slant backs which has a 200 amp alternator and sure enough just tapping the positive battery cable to the positive terminal, a little arc. I tried using my voltmeter to see what the amp draw was but haven't got that figured out just yet.

Meant to drop my original 200 amp alt off at a repair shop today and see if they find anything. Hopefully in the next week or so I can back by there.

 

[Stein12501]

I would love to know what you find out. It seems to be to common problem. I think a lot of times it's overlooked until you pull the battery cable and then you notice the small spark. Again in my case if I disconnect the leads to the voltage regulator and then reconnect the batteries I lose the draw. The second regulator that I used was also a used one so maybe that's my problem. It seems that the controller under the dash is a real weak link and is responsible for several melt downs.

 

[kfrosty]

It seems that the controller under the dash is a real weak link and is responsible for several melt downs.

The S3's from what I perceive aren't supposed to have as many problems, right? Mine had the original prestolite. I probably have just left it in to see if anything happened. But replaced it, glow plug temp sensor and alt because I wanted to want to have issues. That hasn't worked out but then again I still can't finger any one thing yet.

 

[Stein12501]

Kfrosty I know what you mean. You try to resolve the problem before it becomes one and it still bites you. Hopefully we can work the bugs out of these things given time and money! They are still 20 to 30 year old vehicles that have probably sat most of their lives (kinda sounds like me). Again if I find out anything I will let you know.

 

[kfrosty]

I view it as I tried to fix a problem that didn't exist and created one. (Leave well enough alone comes to mind) In hindsight, I probably should have just left everything alone and carried a new control box and Glow Plug temp sensor with me to change out should a problem ever came up. The grounding harness is pretty easy and sounds like a good idea to do up front.

 

[Stein12501]

You have a great point there. My dad always said, "If it ain't broke don't fix it". The ground wire update is an easy fix and you can make it up yourself. I think Retired War Horses had a write-up and someone had a webpage that had pics and everything. I replaced the windshield washer and when I pulled the wires I had trouble with my control box and brake light. They were using the ground through the washer pump is the only thing I could come up with. I ran new grounds and no problem. The gremlins are everywhere.