Found this thread while looking for answers to my own electrical issues. I have an 85 F250 that has intermittent electrical problems. Sometimes when trying to start it, I get a dead key, no power to lights, dash or anything. In those cases, jumping a wire from 3 to 5 as illustrated in the above pic is the only way to start it. Any ideas? I'm getting a bit tired of running jumper cables from the engine to the cab so I can hold the ignition switch in place while jumping it over. I'm about to install a push button on the dash and just leave the wires in place.

 

I don't know what tranny you have, but check your neutral safety switch. If you have a automatic it will be down on the driver's side of the tranny where the lever goes in. If you have a manual, some of them have a switch on the clutch pedal that has to be depressed for it to crank.

 

bypassed the clutch switch a few weeks ago, my problem is a total lack of juice coming from the battery to any part of the truck. No dome lights or anything.

 

Take everything off terminal #3 in the diagram above. Make sure you take terminal #1 off for safety 1st though. At terminal #3 you have the large cable from the battery +, but you also have some smaller wires. One of these powers the whole truck. Make sure it looks ok and is well connected. Fix anything that doesn't look right, and put it back together. If it still does it, then follow one of these smaller wires down from #3 and unwrap the harness. There is usually a splice down in the harness, and sometimes it gets corroded. This main wire branches off to the alternator, and also goes in through to the firewall and feeds the ignition switch and the fuse box. It's the main power wire for the whole truck. The big fat wires are just for the starter motor.

 

Replaced the battery cables, as I was also told that could be the issue. The cables were definitely in need of replacing, but that ended up not fixing the problem either. Found at least one fuseable link that was bad, straight wired it and that didn't help either. Finally ran out of time and wired up a push button switch so I could start it from inside the cab. I think I'm just gonna take it to a shop next week while on vacation and let someone else deal with it. I definitely see a full wiring harness replacement in this truck's future.

 

That's not going to happen, they don't make harnesses for these trucks(yet).

 

yeah, believe me, I've looked everywhere for one. I was thinking of one of Painless Wiring's universal kits.

 

Those universal kits are not that great. You have to splice wires everywhere to hook the original Ford plugs back in to the switches and stuff. So you end up with a spliced up mess that cost you hundreds of dollars. If you are going to end up with that you might as well repair the old harness with splices and new wire where it needs it.

 

Spent 6 hours this evening trying to track down the problem with no luck. Checked every fuseable link I could find and all of them had continuity. Pretty sure its not getting power to the fuse block but damned if I know why. Finally said the hell with it. Gonna take it to a garage next week and let them sort it out. Electrical issues never were my cup o' tea.

 

I like my 51 F1.

 

hey just had the problem you had. 12v everywhere, signal and both sides of the solenoid. It's a ground. Clean the neg terminal. When you lose ground. You'll have12 at chassis grounds cause it's looking for ground

 

Can anyone message me the diagram y'all are talking about.om having the same problems withy 81 f150 but can't see any diagram on here

 

Here it is.