Just got a 1981 f250 ranger camper special, 351m, t18 trans, good looking body and frame..the wiring has been rednecked something aweful. So how should it be wired from battery on...right now I got neg going to the alternator bracket off the battery and off the solenoid to starter..I got dozens of wire nuts and splices and random grounds..how should it be done? I'm going to eliminate the fusable links also and do removable fuses. Also what gauge wire is recommended for each step. I'm used to AC not DC..pictures help! Thanks

 

FYI;
1981 EVTM - Gary's Garagemahal (the Bullnose bible)

Post some photo's of what you are dealing with.

 

 

WOW! That's gotta be some of the worst wirin' I've seen. Your gonna have your nose in wiring diagrams for some time to come to straighten that out. I hope you got a good price on it. Does everything work?

 

How do you plan on eliminating the fusible links? What size fuses are you going to use?

 

Well when I find a fusable link I'll see what gauge wire was used to snap at what amprage load and put in a removable in line one. Yes I damn near stole the truck..guy said it blew blue smoke and burned oil...well I see a oil leak and I can hear retarded timing and a stuck valve..Soo probably easy stuff..compression is good, he just had a heavy duty clutch installed and tires have 15k miles on them.

 

Let us know what you find out.

 

I suggest using a multi meter to determine if those splices at the wire nuts are 12V IGNition. I found on my truck that the previous owner had used wire nuts and soldered rat turds on multiple wires so they were fed 12V IGN. Once I confirmed it with a multi meter I was able to unsplice everything and run the lines to the + side of the starter relay for a solid connection to 12V IGN.

Aslo, it looks like some of the wires under the dash go to auxilliary components. Is that a trailer brake mounted under the dash? If you don't need it you can easily remove it.

Good luck.

 

It's all about perspective. I feel like wire nuts indicate a little foresight on the PO's part. Not really seeing any massive ***** of electrical bandage, I mean tape. Worse ways to go I suppose.

How handy are you on a soldering iron? Personally, I deal with anything harness related with solder and a good mechanical bond, as well as copious amounts of shrink tube, and then tape if i booger the heat shrink process up. I do use butt connectors on terminal ends and anything I deem non essential. The first truck wiring I did was on an '92 ranger that the PO, I assume was 12-15, completely butchered the dash harness installing what I assume was a pretty sweet looking sound system. I'd recommend not starting your mechanical career with a dash pull and harness rewire, but it sure is educational. Sure learnt me how to search truck forums and read wiring diagrams. Mostly time consuming. May run into issues if your wires have been replaced and the colors do not match, still not too hard to connect the dots and see what it was supposed to be. My harness was boogered so bad I believe I put 80 hours in it before I had it looking good. Real proud of myself until I reinstalled the dash and the firewall connector was a half an inch too short.

In my experience, the bodged wiring in the cab will usually be to accessories the PO deemed important, or they'll go no where. Pretty easy to clean up. If you're swapping new wire in for old work you should be able to guess the gauge based on whats around it. Go one size larger if you think you need to, any more than that is probably risky(brain screams bad things can happen if you use too large a gauge, but not sure why). I like to reduce the number of splices to as close to zero if I can.

 

The only thing I see wrong with removing the links and going with fuses is the links are a "slow burn" where fuses are a "fast burn".

Now I am just using numbers to show a point:
If you figure a link wire is say 20 amp load and you pull it and install a fuse of 20 amp that circuit may spike to say 25 amp or a little more for a split second then come back down below that 20 amp setting.
Take the blower motor, I am sure it will spike over its normal run amps when turned on as it will take more amps to get it spinning than keeping it spinning. AC compressor may be the same way?
Now if you find the max amp on start up and install a fuse of that size the whole system could melt down before the fuse blows.

Just my thinking do as you wish.
Dave ----

 

I'm decently handy with wiring and soldering..I install well pumps, booster pumps , relays and contacters for a living ..under the cab is fixed now I need a new duraspark harness and I'm making my own solenoid to alternator harness as the old one was burned up due to over amprage so 8 ga wire and a 90 amp fuse will head to the alternator. I'm considering running power to the cab on a separate line in order to prevent over power burning of wires or circuits. Any suggestions there?

 

Well you passed the test I was waiting for you to put a 30 amp fuse in place of some of the fusible links, that will not work, it's too small. It's hard to beat a fusible link for size and being able to hide it in the harness and keep it out of the weather/environment. As you are doing, if you are going to use fuses you have to use large maxi fuses.

 

So am I able to run 4ga wire directly to the alternator from the positive side of the solenoid or should I just stick with 6ga from my fuse junction that contains the yellow wire and other splices? I'm trying to clean up under the hood and simplify things...seems to me if the alternator had it's own charge wire I couldn't over amp others? Or does this all go thru the voltage regulator?

 

The factory only used 10 gauge for the charge wire. Of course they pushed the limits on their wire sizes. But it is also short, and in open air. 6 gauge should be plenty big enough. Feeding the whole truck's electrical system is one or two 10 gauge wires with fusible links at the starter solenoid connection also. You main load will be charging the battery, and any other regular loads from the truck. If you are adding anything like electric fans or a big stereo amp, you need to wire for them, I would not use the truck's puny wiring for something like that.

The only power the regulator has to handle is what the field of the alternator requires, which is not much.

 

Everything hooks to the same lug on the solenoid, battery +, the ALT charge wire w/ fuse link and 2 or 3 fuse links that feed other parts of the truck.
Dave ----