Hey all. Got a couple of electrical problems that came with my '85 when I bought it and haven't looked into yet other than a casual inspection of wiring which looks good with no butchering.

1) The horn didn't work when I got it. Found out they were disconnected under the hood. Hooked them up, have horn when the key is off. Turn key on and no horn. Doesn't matter if truck is running or not. This is an odd one, I've never run into this before.

2) No cruise control at all. System appears to be all there and hooked up, but is dead.

Any suggestions on where to start would be appreciated.
TIA!

 

Sounds like you have problems in the steering column. I would try running a scrap piece of wire from the engine block and touching it to the steering shaft above the rag joint, and then see if the horn problem goes away. It sounds like you may have lost the ground to the steering shaft.

If that fixes it, you can permanently bolt a short jumper wire across the rag joint to ground the shaft through the steering box.

 

Also, isn't the horn relay on top of the cruise control unit under the dash? I don't know if that could be bad, but I have a few of them boxes laying around. Also, if everything checks out w/ the cruise visually and all seems connected correctly, check the spring loaded button that detects you depressing the brake pedal. That button can be adjusted. For 7 years I gave up on my cruise control only to find out I had to simply re-adjust that spring loaded button. I had cruise again! That button had shifted slightly and it was sending a signal as if the brake pedal was depressed, hence turning off the cruise. Good luck

 

The horn relay is normally under the hood on the firewall between the master cylinder and fender. There's a plactic box that sticks out that holds the horn relay (if with cruise) and fuel pump relay (if with efi).

 

Thanks for clearing that up. But what does that relay looking device do that sits on top of the cruise control unit under the dash?

 

I'll have to take a look...I have a complete cruise unit in a box in the garage. I'm pretty sure these units had a seperate speed sensor. That would be my initial thought.

 

OK, I found the answer per the 3 volume set 85 Ford Truck Shop manual (Body, Chassis, Electrical). "The horn relay used on vehicles equipped with speed control is located under the instrument panel to the left of the steering column and is mounted on the outboard attaching screw of the speed control amplifier module". Wierd, I could swear mine is located to the right of the steering wheel under the dash if sitting in the truck. Don't know if a bad relay would let the horn work in one key position, but not the other. Franklin is a better diagnoser than I am.

 

And you would be right...I have the part in front of me right now and that is a horn relay on top of the box....strangest looking relay I've seen, but a relay nonetheless. Which really makes me wonder what I replaced under the hood in front of the fuel pump relay that made the horn work. But I take issue with the book on the location of the underdash components....there's nothing to the left of the column.....

 

Funky horn problems? Whats it do? Play George Clinton songs?

 

With some occasional Kool and the Gang!

Thanks for the suggestions guys, I'll check out that ground and the brake pedal switch and will get back to you with the results.

 

hhmmm that's interesting about the switch on the brake for the cruise control...i would assume there is a clutch switch for the manual trannys? i have a vacuum module on the truck in my sig if that helps idk if they all came w/ vacuum modules or if some of them were electronic...

 

There is an electric clutch switch for the manual transmission trucks. Its part of the same circuit as the stop light switch switch. Look for light green wires.

 

Follow up: Dave was right, it was the steering shaft ground. The reason it would work in the off and acc positions was the steering lock was providing the ground to the shaft in those positions. Funny thing is the rag joint looks OEM, big steel rivets/pins holding it all together and still have the plastic cover over it all. But I can't see that there ever was a ground strap in there so I wonder where it got it's ground from in the first place? Unfortunately since the joint had no bolts due to the rivets/pins the only way I could see to run a ground was from the clamp bolt above the steering box all the way up to the nut/bolt that's at the union right below the end of the column. So that's where I ran the wire and then wire tied it secure to the shaft. Kinda stupid that it's so long just to get past the rag joint, but that's the way it is.
Not only does the horn now work, but that fixed the cruise problem too. The cruse works now, although kind of weird, it shoots up 8mph after I hit set, but at least it's working.

Thanks again for all the help!

 

I have heard, but never seen it for myself, that there is a rubbing block down in the column that is supposed to ground the shaft. I hate working on steering columns, and take them apart as little as possible. Maybe someone else knows more about the rubbing block. I bet though, if you do find it, that it's not available and you would have to run a wire around the rag joint anyway.

 

I noticed my dad, who always did the steering columns himself, hated them too, Franklin2. Wish I knew more about them than I do. He always just cursed and did them right in front of my face. We never worked on many Fords at ALL. I swear, maybe a slave cylinder once on a truck here or there...