Need some guidance after a major wiring meltdown

[Rvitko]

I have been estoring my m1009 and for the last two weeks I had the dash apart to install a nostalgic air ac kit and clean up my wiring. I changed the turn signal switch, combination switch, ignition switch, cleaned all contacts, opened up the fuse box and cleaned it, changed all fuses and flashers.

reconnect batteries and start truck, everything worked.

I moved on on to installing the evap box for the ac, no wiring, just mounting it which meant removing the heater core/box.

get it installed, heater back in, go to start and runaway ignition, the batteries got very hot and are deformed, the terminals for the battery connectors melted, starter, alts, fusible links all smoked and burned (and the starter was an nos 27mt that I shimmed and installed myself on a new flywheel, the bracket and heat shield are present, the alts I rebuilt myself about a year ago and even replaced the boots over any terminals)

i did the doghead mod to the letter one year ago with the exact relay as shown and i used liquid electrical tape and rubber caps on the tops of the terminals.

 

[Rvitko]

So, question is where did I screw up. The ignition switch worked twice, when it locked on the key and linkage still moved but did nothing. Thoughts I have are defective ignition switch, accidentally jostled something loose on the firewall 24v side working on the heater, something went wrong in the fuse box, batteries did something weird? Not a single fuse blew.

fwiw, my turn signal and multifunction switch were flaky, I changed them due to intermittent issues with the turn signal not staying on and wiper speeds not working, ignition switch worked but I changed it because I was in there and I used a 1404b 1990115 which was a real gm made in USA. It was the one for a 1985 diesel 6.2 blazer they had listed.

i am very puzzled as to what happened, I want to make it clear that to me the doghead mod is blameless, it worked for a year, hundreds of starts and I appreciated the positive thud of it engaging.

 

[Rvitko]

I wanted to add some other details of the incident. The battery terminals were on tight, not just slipped on. The starter chugged to a stop in under a minute, probably 30-45 seconds. Since I did not have the lower trim or dash face plate installed, I could visually confirm the linkage moving and it had successfully started and ran earlier that day once the column switches were done. I cleaned every single plug and switch contact, and my glow plug card is the new style with diagnostic lights bought from hillbilly wizard. Within 15 seconds I was out of the truck, I was running for my wrench set to disconnect the batteries, I had just turned to preglow and the starter engaged and no amount of turning the key was stopping it. I hesitated because at about 45 seconds the solder shot out of the battery cable terminals like lava and the terminals were completely melted on the front battery negative and rear battery positive. The batteries were also hissing steaming and bulging. The alternator and starter wires smoked at about 60-75 seconds, fusible links near the glow plug relay done at about 90, got the ground wire off the front battery terminal at that time. The wire between the two batteries was nos and still looks good, terminals are fine, the other cables seemed home made but this was a ft hood vehicle I bought 2.25 years ago from a guy locally who bought 2 at auction and just flipped them, it was untouched. I have put a few thousand miles on it and changed all fluids, all hoses, etc, been working down the list of debugs and maintence. The main cables were on the typical milsurp terminals you see from various vendors and I had to unbolt the cable from the terminal to kill it.

 

[MarcusOReallyus]

Pretty hard to troubleshoot something like that over the Internet. I can only offer a few thoughts:

Solenoid decided to lock up all on its own, with no help from the relay. With what's left of your batteries disconnected (they are history anyway), put a meter on that thing and see if it's shorted.


Start at the beginning repairing the damage (you'll need new cables, I think) one step at a time, and you may find the culprit.

 

[tim292stro]

Indeed - it'll be hard to do a post-mortem over forum posts.

Did you in any way tamper with the control wiring of the doghead relay during the A/C install?

It does unfortunately sound like you'll need to replace a rather long list of wires and devices in the truck now that some damage has been done. It can be discouraging, but we're here to help and support you .

 

[rustystud]

I would also check those glow plug relays. Mine had melted the whole wire loom before I got it from GL .

 

[Foxtrot Oscar]

Seems to me the CUCV is voted the Worlds Most Likely Vehicle to Melt Wiring.
I read all these tales of woe where batteries melt, wiring melts, fuses blow, starters runaway, etc. and I think I'm becoming paranoid and afraid to insert the key in my ignition let alone turn it to 'Start'.
Can somebody post some reassuring good news ??

 

[rustystud]

Seems to me the CUCV is voted the Worlds Most Likely Vehicle to Melt Wiring.
I read all these tales of woe where batteries melt, wiring melts, fuses blow, starters runaway, etc. and I think I'm becoming paranoid and afraid to insert the key in my ignition let alone turn it to 'Start'.
Can somebody post some reassuring good news ??

A lot of the problems stem from the fact that this truck was originally designed for 12 volts, not 24 volts. The military added on a lot of stuff like two heavy duty batteries, dual alternators and some large relays for the glow plugs. If you don't pay attention and just let your truck go then loose wires and chaffing wiring can cause some serious trouble. Dirty engine compartments also contribute to this. When there is more dirt then engine it's hard to see trouble areas. My truck was a prime example. It was so muddy I rented a steam cleaner to clean it. Then when I could actually see the wire loom I found the relays had gone bad and melted the wiring causing a fire that helped destroy the rest of the wires and alternators and control modules. That was when I just decided to remove the engine and totally rebuild the front end. It now looks like a regular Chevy truck since I also replaced the front grill and bumper and light assemblies. I also replaced the dash. I left the dual battery trays and heavy duty radiator.

 

[Rvitko]

Well, the day after the shock wore off I am going to get to it. I will replace the ignition switch with one I found milsurp, which is a 1404a, oddly the only difference I can find is one has an updated accessory circuit and I would assume that would be the b model. Both are for non tilt column, the a variant was used in most gm cars of the late 70's b was for the 80's. I will need to rebuild the alts, change most of the heavier harnesses, get the starter rebuilt and replace a few fusable links and of course new batteries.

The he bummer is I had done all the steps to prevent this. Doghead relay, I had cleaned all grounds, I had also steam cleaned my engine bay, I had painstakingly tracked down any clamp, clip, bracket that was missing and a source of wear or vibration. I had put in 60g glow plugs and a new U.S. Made relay for the plugs.

My gut feeling is that something shorted on the firewall buss bars or the starter solenoid stuck. I checked the doghead relay and nothing was loose. I did that very well, every terminal was sealed with 3 coats of liquid electrical tape and then a rubber cap placed over the connections. The last step I was on was removing and reinstalling the heater core and box. I may very well have gotten some coolant on the starter in just the right place or moved something just enough on the buss bars.

The he next go around I am going to figure out a kill switch system.

 

[Rvitko]

I am satisfied I found the culprit. I have removed the starter and I removed my batteries. While I plan to rebuild the starter(s) (I still have the original I pulled and was planning to rebuild) and alternators myself I went to the local starter/alternator shop to get new batteries and parts and showed the guy what I had and discussed the issue and he was very familiar with military vehicles and 24V systems. Essentially, I had a bad ground post on the front battery, my voltage dropped, the amperage shot up and essentially the starter arc welded the contacts on. Nothing was faulty in my work, just bad luck and bad batteries, batteries that ironically were load tested not but 6 months ago, but they were original 6TL's made in 2009 and I was skeptical of them and intending to replace them anyway but after the all clear I put it off figuring I could finish all the work and then put in fresh batteries when I was done. The only questionable work I found was that the ignition/starter switch has about a 1/4" of play back and forth by design, it is something you have to get right when you put it together by tightening the bolts with the positioning right, I hadn't gotten the position just right so preglow was not matched up precisely with preglow position in the tumbler, so it started in preglow for that reason. Painful lesson I hope others can learn from. On the other hand, I believe my truck will be better for it as I am now going to change the fender liner and main cables so that much more will be new and nice.

 

[98G]

Thank you for posting the ending. Too often these things are left hanging

 

[Rvitko]

Yeah, that bugs me too. I don't post much unless I can offer some real help, but as a resource the forum is much more useful when you can see what worked or didn't.

 

[AZK9]

Yeah, that bugs me too. I don't post much unless I can offer some real help, but as a resource the forum is much more useful when you can see what worked or didn't.

Well... I've read through this thread and after feeling, almost sick myself, because of the difficult event
you experienced... I'm very appreciative of the info you've shared and EXTREMELY happy you solved the
problem.

I'm still in the planning stages of doing electrical work on my M35A2 and efforts and postings like yours
are helpful to me.

Thanks for sharing and my best wishes for the successful completion of your electrical work!

 

[bwilson7990]

I found was that the ignition/starter switch has about a 1/4" of play back and forth by design, it is something you have to get right when you put it together by tightening the bolts with the positioning right, I hadn't gotten the position just right so preglow was not matched up precisely with preglow position in the tumbler, so it started in preglow for that reason.

The 1/4" of play that you described here in the ignition/starter switch- is the play oriented forwards/backwards or in/out? I ask as I had gotten into the steering column of my 08 to clean the horn contacts and replace the turn signal mechanism and it seems that my ignition switch is now sticking out of the column maybe an 1/8" or so. I couldn't get it to sit flush again. It works fine so I left it as is. Note: I don't have the stock GP controller, my system is manual on a momentary push button switch. I'm just making sure that the little bit that the ignition switch sticks out from the column isn't what you were describing.

 

[Rvitko]

The ignition switch mounts with two bolts, one is an odd one with thread top and bottom that another nut goes on to secure the high beam switch bracket. The holes cut in the side of the ignition switch are oval and give a range of play for installation but that is front to back, not up or down. When you are installing a new switch, it has a plug locking it in the "lock" position, so you can line everything up and then pull the plug. I messed with it a bit after that which is clearly a mistake.

From what you are describing I think you are talking about the ignition key cylinder, what I was describing was the actual switch at the very base of the column that the key is actuating via a linkage. If you are talking about the key cylinder, it was likely tampered with in the past, perhaps the screw that secures it was removed so all that holds it is the cog on the tumblr and that is basically in a ramp so it can move in and out with key position, if I recall correctly it pulls out in the accessory position, but if the screw is in place you can't pull it out and it won't move much at all. The screw is in their with the turn signal switch and other stuff.

 

[bwilson7990]

Okay cool that's kinda what I had in mind but wasn't sure. I'll take another look and make sure all looks good. Thanks

 

[Rvitko]

If you need a new cylinder or parts, I worked with a guy in Georgia and I can get you his info. I picked him because he was able to get me new door cylinders, ignition cylinder and tailgate cylinder matched to a single CUCV style key in black finish and he was very fair and friendly, it was less than my local locksmith was going to charge to rekey and repair what I had and it was a PITA as we had to use 3 brands of sets to make it happen, the tailgate cylinder is a hard one to find and only the doors are original Briggs and Stratton brand cylinders as they no longer made the ignition cylinder with the black finish.

That screw that holds the cylinder in is an odd one, a roughly 3/4" long pin and at the top is a very coarse woodscrew like thread, it is right above the upper right shoulder of the turn signal switch. I think it was a T15 head if I recall. You will see it where the cylinder outline is visible.

 

[Rvitko]

Just to update everyone, I am back up and running. I rebuilt the starter myself as well as both alts (for the 2nd time) with parts from asp wholesale. I have to thank Warthog for his fusible link instructable in the faq. New 6tmf batteries and cables and frankly, I am glad this happened. I made many repairs including fixing up my battery trays, replacing the wheel well and cleaning the buss bars and underhood ground points. The lights inside and out are crazy bright now. I have one residual electrical gremlin. If I turn the turn signal left both dash signals come on solid, right, no signals, yet in both case the external lights work properly and blink on the correct side, the hazard lights don't blink and both come on solid on the dash, flashers are new heavy duty, bulbs are new, turn signal switch is new.

 

[tim292stro]

First, thanks for continuing to let people know how this is turning out - sometimes people get the fixes they need and don't let people know what worked, so it makes it harder for the next reader to figure out what they should do.

I'll admit that gremlin is a difficult one to debug remotely (and having kids jumping all over me today isn't helping my focus ). Best I can recommend at this moment is to use a test light to check the wires coming out of and going into each device. If you haven't already, pull the dash and cluster so that you can get to the flexible circuit on the back of the gauge cluster. If the copper on the flex-board corrodes you can have some wonky behavior.

 

[Rvitko]

Thanks, it was stupid simple. I have one loose copper leaf on the socket for the cluster, it had folded over and touched the one next to it. 100% now. I can finally drive it again. I have a new hood for it at work so that will be the next project.