I feel dumb asking this, but I was recently handed down a 1976 F-100, and I'm in the process of getting it running again. Well I'm trying to check all my fuses, but I have one major problem. I can't find the damn fusebox. I found the one inside the cab, that was easy, but I'm assuming there should be one under the hood as well. Thats the one I can't find! I searched throughout the engine bay (even climbed underneath and looked around) and still can't find a thing. Am I totally missing something? Is there even a fusebox under the hood for this year and model truck? If anyone has any info, I would highly appreciate it.

 

i think im 95% sure my 76 f100 only has a fuse panel in the cab. I think ya might be looking for somethin that dont exist. I cant really check mine at the moment though, kinda far from home.

 

Nope, there isn't another fuse box. What you see is what you get. These old rigs didn't have too many bells and whistles, so things were a lot simpler when they were built.

 

Ok good so I'm not just losing my mind. I was seriously feeling like I was just missing something. I have no electrical at all right now even with a brand new battery, so my first thought was to check all the fuses. I started using a multimeter to find out where the current stopped, and didn't get too far. I found that theres current going into the starter solenoid, but nothing coming out the other side. So I will be replacing that today to see if that fixes the problem. Thanks again guys.

 

Be sure and check the fusible links. If you lose one of them it can cause the whole system to be dead, too.

Electrical trouble-shooting is a pain, but if you do it systematically it usually isn't all that bad. Good luck!

 

Ok cool, will do. Thanks for the advice, I appreciate it. I'll let ya know how it goes.

 

Ok so I found a fusible link that was burned out and obviously needs to be replaced. Problem is I'm not sure what to replace it with. The label on the wire itself said "Fusible Link 6 GA." So I figured ok I just need to replace it with another 6 gauge fusible link wire, but I've searched AutoZone, PepBoys, O'Rielly's, Napa, Carquest, RadioShack, and Fry's Electronics. Not a single one of them has any 6 gauge fusible link wire or even just 6 gauge wire in general. I did find some 10 gauge wire at a few of these places. Would I just be able to replace the burned out section with 10 gauge? I know that with a fusible link you are supposed to use wire that is two sizes smaller than the wire you are trying to protect. Being that the label said it was 6 gauge, does that mean I should be using 10 gauge to replace the burned out section? Also do I need to replace the whole wire or can I just use connectors to replace the section that burned up?

 

First time poster here: I just bought a 76 F-100 Supercab, at a steal, but the brake lights and turn signals are out. The turn signals do not even show in the cab. The tail lights do work. Is this a fuse or wiring issue? I have a buddy who's an electrician and he's gonna check it out with me, but I was hoping to get an idea here first.

Also, the car was not running when I arrived today. The owner said the ign module was fried. I picked up a new one, jumped it, and off I went. He said that he had bought a few modules, and they kept frying. Ideas? Will I be sending too much voltage through the system as well?

Any help is appreciated.

 

First, welcome to FTE, lot's of good knowledgeable people here.
The brake lights work through the turn signal switch. It's possible there is a problem in the wiring going to the t/s switch or the switch itself is bad.
Go here for copies of the FACTORY wiring diagrams:
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
As for the modules, don't go with the cheap off-shore modules. They are prone to early failure or bad right out of the box. Stick with Motorcraft, they're more expensive initially but buying one Motorcraft is cheaper than buying three or four "cheap" boxes.

 

Anytime you are frying modules regularly, it's time to look at the voltage across the battery terminals with the engine running. Sometimes the voltage regulator can let go and run the charging system at too high of an output; in this case onboard electronics (such as the ignition module) are the first thing to go.

 

Take a close look at that fusible link, it should be marked 16 gauge, not 6 gauge. FoMoCo never offered a 6 guage fusible link for any 1970's vehicles.

1973/79 all FoMoCo Passenger Cars/F100/350's/Bronco's and Econolines:

D3AZ-14526-J .. Fusible Link-9" long, 16 gauge, wire color green with both ends stripped.

D3AZ-14526-T .. Fusible Link-9" long, 16 gauge, wire color orange with eyelet on one end, stripped wire on the other.

 

correct me if im wrong, but i think u can add an inline fuse to do the same thing that a fuseable link does.

 

Yes, you physically can do this, but I don't recommend a fuse for this application. Not sure why this is coming up; the original post is old, and a new user responded to it with a different question.

 

Thanks a lot guys. I will look at both issues on Friday. Like I said, I have a buddy who's an expert with electrical issues, so he should be a big help. What's the best way to check for too much voltage production?

Also, I've been reading other forums where the t/s switch goes out, and people just dowse it with WD40 then it magically works...any thoughts on that?

 

Use a voltmeter across the battery posts and measure the voltage. With the engine off the voltage should be around 12 volts. With the engine running the voltage shouldn't be more than around 14.7 volts. If it's much higher replace the voltage regulator.
As for WD-40 "fixing" the trurn signal. I don't have a lot of faith in a repair when things magically fix themselves.