CUCV wiring woes

[jaytee]

So my 85 1009 K5 CUCV is giving me fits. I bought it a little while ago and it had a ghetto 12v conversion on it. As far as I could tell, the batteries had been re-wired to parallel, the starter had been replaced, the passenger side alternator had been unplugged, and the resistor bank behind the air cleaner had been removed. The glow plugs also have a manual switch hooked up on the relay, run through the firewall, to a button on the dash. It works fine still.

So I followed the instructions from the Michigan Fire Brigade .pdf that is so popular for 12v conversions. I chose the option with the single alternator. Everything seemed to be fine until I started tried to crank it. The cluster lit up and such as usual when I turned the key to run, but when I turned it to the crank position all ignition powered everything died. I checked the fuse box, replaced the popped 10A fuse for the ignition, nada. So I checked the harnesses that plug into the ignition switch. Both of the red wires are hot, so I guess it is getting the proper power. I replaced the ignition switch, nada.


I looked at the wiring under the hood to see if I screwed something up, but it looks good. I noticed that the purple and purple/white wires had both been cut at the harness on the firewall and all four spliced together with one big butt connector. Ugh. I fixed them and now each wire is soldered together, separate from one another.

I unplugged the starter relay harness and verified that the starter will crank if I hook up a jumper across the terminals to the solenoid wire. So I guess the starter and solenoid are still good.

I have no juice on the pink ignition wire that goes to the injection pump cutoff, and nothing on the same wire at the fuse box (that pink wire seems to go everywhere).

Any suggestions? This thing makes me feel like an idiot, and I need my daily driver again.

Should I re-wire everything manually? If that will work and it will charge, please tell me how. Should I light it on fire and push it into the ocean? Should I just start replacing stuff?

 

[devilman96]

Not to kick you while you’re already down but this is the crappy part about trying to convert a 24V system to 12V and why I say it’s a big no-no... Especially on a CUCV which gives you the best of both worlds 12/24V! Once you get into it your conversion it really does become YOURE conversion... None of the normal rules apply anymore and tell one what is wrong on a one of a kind jobber is pretty much impossible.

If it is that bad of a hack job and too much to go back to 24V with I would suggest getting a OEM or aftermarket 12V harness and dropping it into the truck... OR find another 24V harness and start over… It really is your best bet for ending the nightmares of gremlins and escaping magic smoke as there really isn’t anything better than a 24V CUCV that’s being maintained.

…and speaking of magic smoke… check the fusible links.

 

[jaytee]

ok so its not an open, it looks like a short

no juice at the on the pink, so I hooked up a jumper from the hots at the ignition switch but didn't attach it to the pink, and I got what I expected, 12v

as soon as I plug that wire into the pink, I get 20mv, it drops down

when I unplug it from the hot source, it drops off again to 0.00v. Dead. So, its a short somewhere. Now I have to find it.

Sigh............

 

[85-m1028]

Re: RE: CUCV wiring woes

Not to kick you while you’re already down but this is the crappy part about trying to convert a 24V system to 12V and why I say it’s a big no-no... Especially on a CUCV which gives you the best of both worlds 12/24V! Once you get into it your conversion it really does become YOURE conversion... None of the normal rules apply anymore and tell one what is wrong on a one of a kind jobber is pretty much impossible.

If it is that bad of a hack job and too much to go back to 24V with I would suggest getting a OEM or aftermarket 12V harness and dropping it into the truck... OR find another 24V harness and start over… It really is your best bet for ending the nightmares of gremlins and escaping magic smoke as there really isn’t anything better than a 24V CUCV that’s being maintained.

…and speaking of magic smoke… check the fusible links.

converting to 12v is simply removing one alt, rewiring the batts in parallel, and swaping in a 12v starter. thats so complicated!

 

[jaytee]

RE: Re: RE: CUCV wiring woes

so I figured out that if you pull fuse #20, the "ENG CONT" fuse, then the short goes away. So my draw is somewhere on the back end of that. One of the things it powers is the seatbelt warning buzzer. I pulled that but it didn't solve the problem. The only other things I see drawing power from that are the "water in fuel" solenoid and the cold advance and fast idle temperature switch.

WHERE IS THE COLD ADVANCE AND FAST IDLE TEMPERATURE SWITCH AND WHAT DOES IT LOOK LIKE?

 

[85-m1028]

thats a little green wire that ends at the injection pump and daisy chains back to the temp switch "that switch is in one of the heads right next to where a glow plug screws in"

there is a cluster of wires by the fuel fiter, check all those connections and make sure you don't have any fuel leaking on the wires, that might create a short.

check the alt wires that were disconnected and make sure theres nothing grounding out.

 

[dependable]

Fast idle temp sensor is off back of passenger side head. Follow wire back from kick down soleniod on injector pump. looks similar to regular temp sensor, as I recall.

 

[jaytee]

So I followed the juice out, disconnected the fuel filter assembly and the cold advance and the draw is still there.

Back to the drawing board.

The only other place that the current goes in that circuit is up to the instrument cluster, and the wires themselves. I'm going to call it quits tonight, tomorrow I will start testing the wires. Hopefully its not up in the instrument cluster I guess. I will unplug it and see if that makes the problem go away.

Thoughts?

 

[jaytee]

anyone in the Baltimore/Washington/Maryland area have a CUCV that I can use as a reference to look at for my wiring? I think mine has been hacked up and I need a reference, 24V or 12V would be helpful

 

[mangus580]

Re: RE: CUCV wiring woes

converting to 12v is simply removing one alt, rewiring the batts in parallel, and swaping in a 12v starter. thats so complicated!

its not always that simple, as nobody seems to every do it the same. Thats why once someone tells me its a 12v convert, I pretty much toss my hands up and say 'sorry... cant help ya much'

 

[mangus580]

anyone in the Baltimore/Washington/Maryland area have a CUCV that I can use as a reference to look at for my wiring? I think mine has been hacked up and I need a reference, 24V or 12V would be helpful

Wiring diagrams are in the TM section..

 

[jaytee]

yeah I have wiring diagrams, thats what I have been using thus far, but I was just hoping to have a reference to look at for how my truck is supposed to be, a model or something like that

 

[jaytee]

OK so if I hook up a jumper from the hot to the pink ignition wire coming from the switch, but pull the fuses for the ignition powered items and pull the connector on the injection pump, I get that 12V potential still. However, as soon as I hook any of those three things back up, either one of the two fuses or plug the injection pump back in, I lose that 12V potential. Isn't that BAD? None of those items actually power up, turning on the ignition kills it. That makes me think

1) there is a short some where

or

2) putting the load on it trips something.

I first thought it was a short, but since putting ANY load on it kills it, that makes me think that it is tripping something somewhere, like maybe a fusible link that isnt quite dead until you load it?

is there some sort of relay or breaker that i am missing?

 

[jaytee]

okay I have started re wiring the whole thing, from the battery all of the way through. I undid all of the looms so that I could trace each wire from start to finish, and test with a multimeter. I have replaced some of the fusible links already and will probably do the rest. Those things are hard to find, especially the 12 gauge ones.

I have found a bunch of old wires that were corroded on the inside, nothing that should cause this problem but hey why not replace it while I have it apart and I have the materials.

If, in this process, I do not find the cause of the problem, I am going to be really ticked off.

 

[jaytee]

Hey while I have it apart I was thinking of taking out the STE/ICE port and the wires for it. Has anyone done this? Are there any implications or problems with this? I don't use it, never will, and I am trying to simplify my wiring in the truck, to where it is just the essentials for stopping and going and such.

 

[dependable]

If you want to keep it simple , mess with your wireing harness as little as possible. if the STE/Ice port is not bothering you, don't bother it Cutting it out could cause a world of hamberger with no gain. Also, altering the wiring will lower it's resale value.

 

[jaytee]

I decided to keep to STEICE port for now. The rest of the wiring is DONE!!!! It turned out great! I re-did a stock style wiring system, converted to 12V only, with new wire/cables/connectors and its sweet! The problem of the ignition circuit juice looks to be solved. The truck is all hooked up and ready to run but I have hit a new speedbump. See my new post about the starter. Sigh........