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What can cause complete power failure on a truck? HELP, STARTER? UPDATE POST 15

Dabba

Dabba

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This is for my 86cucv. I shorted one of the batteries agaist the mounting bracket and i burned up a cable end and 2 fusible links. Replaced them all, got my voltmeter out and checked i had 24v across both batteries which i did (cucv system) But i still have no power to the truck at all. No horn, no lights, no nothing, just dead, but the batteries are fine. I figure logic would dictate theres only a few things that can kill power to the entire truck, so if you guys could let me know what those are and how i check em with a voltmeter, that would be great. All wires under the hood look intact. Maybe im missing a fusible link somewhere?
 
Do you have power at the small distribution block above the air cleaner on the firewall? (its near the GP relay)
 
Jesus wire to the main fuseblock. Small wire off the battery to a block on the firewall then to the fuseblock under the dash. If it ain't that, it's probably something else.
 
not to sound like an idiot but how do i check those, im used to checking complete circuits, like positive on one batterry to neg of other battery and i get 24v, or i check the wire for any resistance to see if its good, but using the voltmeter, how do i check those locations. Sorry but im a complete idiot when it comes to electrical (well for the most part) Its gotta be a wire or link right? cant be some sort of main fuse or anything simple? (haha simple..)
 
i had a similar problem on my last vehicle. i ended up having to rewire the entire charging system from the battery to the fire wall connection. hope this helps.
 
Dabba said:
not to sound like an idiot but how do i check those, im used to checking complete circuits, like positive on one batterry to neg of other battery and i get 24v, or i check the wire for any resistance to see if its good, but using the voltmeter, how do i check those locations. Sorry but im a complete idiot when it comes to electrical (well for the most part) Its gotta be a wire or link right? cant be some sort of main fuse or anything simple? (haha simple..)
Click to expand...


Put the red lead from your multimeter on one of the dist. block terminals and the black lead to a ground (really just anything metal attached to the body).

I'm betting that you blew the fusible link from the rear battery to that dist. block.
 
DR said:
[ If it ain't that, it's probably something else.
Click to expand...


:haha::haha::haha:[/quote]

I used to train Cable repair for SBC which can be quite frustrating at times. Quotes like that relieve stress.

A friend of mine from HS (1967) worked at the ACE Hardware in Coolidge and played Bass in that saloon just down the street. Band was called Sonoma and I believe Hiway 87 for a time. His name was Don Alfrey and I believe he died last summer at the age of 58.
 
Okay well, i think im getting closer to the problem...

I go out tonight to test the ground off the front battery and it checked out. I figure i may as well test the connection from the battery to the firewall connection on the drivers side (dist block? i already replaced the fusible link there by using a 12g wire and wire butts). I was only getting 6 volts to the connection on the firewall, So i pull the plastic on the butt connection back and touch the main wire (not the new 12ga i put in) and read 12v, so im guessing my electrical work was bad. As im doing this i hear a "click" and realize the glow plugs came on. (left the ignition in "on") So i place the meter back on the firewall junction and its now 12v. Well since it now works for the momment i decide to try to crank it over. I turn the key and i get a rapid succesion of clicks (same thing i got before this issue happend) and same pretty big sparks from the batteries. I quickly turn the key off and go out and check out what happend. It looks like the positive terminal on the front battery and the positive termninal on the rear battery melted. Thank god i kept the terminals on loose because the rear battery positive popped off after sparking for a second or two, or else i probably woulda blown the links again.

I assume i have a short somewhere, a pretty bad short. Any idea on where i should check first? Should i also assume its somewhere in the starting system being it only happend while i was cranking? Thanks for the help thus far.
 
Didn't you have your starter off recently with the whole mud thing? You might want to check all of that wiring.

Or, since you aren't really up on this electrical stuff, is there anyone near you you can call to come check it out for you?
 
my stepdad is good with electrical but is going to be busy for a few days. Could a bad starter (or a 12v starter in a 24v system) cause this? Yes, i did have my starter rebuilt when i brought it in the mechanic, and after i blew the links i called him up and asked him if he was positive he replaced with a 24v. He swore he did. Could this be the starter? If the starter was shot or was a 12v in place of the 24 i just expected a few clicks, dead starter or to fry the starter at most, not fry my whole electrical system.. So, starter is the next step. Should i just pull the cable and see if im getting 24 to it? Or should i take the starter to a shop to make sure its 24v, or is there an easier way? Thanks
 
I would first verify that all your wiring to the starter is solid and not melted out.

Besides that, when you shorted everything out, you might have blown your starter relay. There's so many things that could have gone wrong, without being there with a multimeter, its hard to trace.

I hoped you learned a lesson here though - proper battery tiedowns do serve a purpose!
 
well i have the voltmeter.. Yeah, i definetly got tiedowns but apparently it wasnt the battery shorting it out, or i have another short now, because its doing the same thing as it did the first time. Again if i blew the relay i would expect it just wouldnt start. After i tried to put positive terminal back on all i would get is a massive spark, even with the ignition off. So i dont get it. She was fine and i had power until i tried to start it(ignition on), went to start, got the short, turned ignition off and batt cable pulled, and when i tried to put it back on, now i get sparks. I guess ill check the starter cable then relay but after that im clueless
 
Andddd im even closer to the problem. I got all my accesories working, but she just would click alot and melt the terminals when i went to crank it. So i disconnected the wire to the starter, went to start and just a click from the relay. I put the wire back on the edge of the bolt its mounted to, went to start and got the clicks with burn marks on the bolt and eyehole of the starter wire. Guess im taking the starter down and getting it tested. If it needs a rebuild im making the mechanic pay for it. I bet its a 12v..
 
Even if the starter is a 12 volt starter it will still work but will just spin faster. The same goes for using a 6 volt starter with a 12 volt system, the starter just spins like hell. This is common with the old car guys, they keep using their 6 volt starter even though they've upgraded to a 12 volt system.
 
Since you mentioned starter I can tell you that when I lost all power to my truck it was a bad starter terminal. Something like 95% of all the trucks power goes through the starter first then to everything else.
 
The starter terminals fine. The wire is also fine. I did not check my grounds. But im done for the day and the starters off the truck so ill have it tested monday, Apparently autozone just has a 12v starter tester, they threw it on anyway and just got a click so cant tell if its bad or 12v wont spin it. I know a 12v starter will work in a 24 system, its just how long it will spin until it blows. The outter casing says 24volt but who knows what internals they used (if they rebuilt it at all, looks untouched) Im also kinda pissed because i had them look at the rear main which they said is fine, but theres a thin film of oil on my inspection plate. I really dont know why i paid him, if its blown im making him pay to replace the starter, and put it on because that was a bitch to take off.

If i have time tommorow i can check the grounds, where are they located?
 
Not sure on military trucks,but here goes.From the head(pass.side rear)to the firewall,negative battery cable to the block(alternator bracket)and smaller 10 or 12gauge wire to core support,firewall to frame and/or rear bottom drivers side cab to frame,and bed to frame.All trucks are different because you never know what the PO has done.The locations listed are the ones I made note of on my truck and others that I've scrapped.

Also,alot of times,the ground straps are corroded causing a bad ground.rust on the ground strap terminals and the mating surfaces cause bad ground also.If anything of the sort is found,they(ground straps) should be replaced if really bad,and the mating surfaces cleaned up.

I'm in love w/ my angle grinder and put it to use with a flap disc to make quick work of rust scale removal.But sand paper,wire brush,wire wheel on drill,etc,will all work.

Another thing to check with the starter.Make sure there are no wires pinched between the the starter and the block causing a short. The the block is the ground for the starter,so be sure the mating surfaces are clean and free of grease,oil,and sludge.

I think I've covered all the bases to the best of my knowledge.If anyone has anything to add,or if I'm mistaken about anything,feel free to correct me.Good luck.
 
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