Horn doesn´t work!

[Florian]

Hi!

The horn on my 71 F100 does not work. I´ve got no clue when it comes to wiring, so what can I check first?

Thanks!

[71PA_Highboy]

Check the horn relay. It is between the starter solenoid and the battery.

Have someone press on the horn switch and feel for a click.

Also run 12V to the horn contact to see if it is good.

This diagram is typical: http://www.fordification.com/tech/wirin ... master.jpg

Hope that helps.

[Florian]

Okay, thanks so far! I´ll try and see what I can do.

The previous owner said something about I had to hang in a bowden cable in order to make the horn work again. Any ideas?

[fordman]

the horn relay is usually the last thing to go bad on these trucks. take the horn pad or ring off and look at the horn bruch inside o fhte column. if you have a horn pad then you will have to take the wheel off to see the horn brush. it is the most breakable thing on these trucks and the most common to go bad or be missing.
horn brush location http://www.fordification.com/images/for ... tainer.jpg
horn brush http://www.fordification.com/images/for ... ontact.jpg
i couldnt find any pictures of the horn brush location for thr 71 72 trucks. but it sits in the turn signal switch. and looks like the picture above.

[Mach428]

I put PS on my truck and in the process, rebuilt the steering column. When removing the column, there was a copper conducter between the rag joint connection that grounds the steering shaft to the steering box, which broke upon removal. When I put everything back together, the horn didn't work. I checked EVERYTHING.

Finally, I put a copper wire from the bolts at the end of the steering column shaft to the rag-joint connector on the steering box shaft. The horn works perfectly.

The moral to this story is that the steering shaft (in the column) must be grounded to the chassis before the horn brushes can work. To check, simply clip a jumper cable to the steering shaft rag-joint bolt and connect the other end to ground. If the horn works, the copper conductor is broken and you can fix by installing a copper wire as explained above.

[fordman]

good post there i forgot about the ground strap across the rag joint.

[Florian]

Thanks for all the good tips!

[ForingaMex]

Mine never had that ground strap but the horn still worked. Do you suppose that it grounded through the bearings?

[Mach428]

Quite possible depending on the year. My steering shaft has plastic sleeves between the shaft and bearings, which must act as an insulator to the shaft. I had one other column apart and it used a ball bearing mounted in a metal race, which would've provided a ground of sorts.

My post was only meant to advise folks that this can be a potential problem for non-working horns and to offer an easy way to check it out without disassembling anything

[fordman]

yes the ground strap across the rag joint was a new thing i think ford started in 1970 or 1971. maybe it was 1969. soemone pelase update the correct year for us.

[killakobra]

must be 70. my 69 had no such thing and the horn worked

[Mach428]

My 69 truck was built in Ontario very late 1969 (June) and some of the parts are 70. The cab for instance takes a 1970 cowl lacing, and my truck does not have the rear hood braces mounted on the firewall, which were common for earlier models. There are other oddities about my truck, which coincide with a model year change.

My father ordered this truck from Ford so it's been in my family since new (i've owned it for 35 years.) So your estimate of this device being 70 or later may very well be true.

Strange huh?

[killakobra]

i thought the cowl hood supports were 67 and early 68 only

[fordman]

yes i have never seen those supports on anyhting but 67 or early 68.