Still having problems with horn working on 1972 GMC

[Jobe72]

Ok gang,

I've done everything I know how to do, checked everything I know to check but I still can't get my horn working in my truck.

Worked fine when I got the truck 1.5 years ago then slowly it stopped working altogether. I've replaced the horns, checking the wiring for a short, replaced the horn hardware and the relay.

Currently it either does nothing or makes a buzzing sound at the relay.

I'm about to put my own horn button in the middle of my center cap and call it a day but thought I would try one more time to get the factory one to work. My truck is out of inspection because of this and it's my daily driver.

Thanks for any help you can give me
Bryan

[cdowns]

where the horn mounts to the core support take it off clean both sides to bright shiny metal and reinstall horn// that is your ground

also while you're at it spray a good shot of WD40 into the horn bell

[eightbanger]

Do as cd said, and also if you have them out give them a good few whacks with a hammer to loosen any corrosion on the internal contacts, I have also found that loosening off the small tone adjuster on the shell helps set them off again, it's good to do this with a car battery handy so you can bench test them as you go.

This is what I did and it got them working...BUT! recently they started to fail again, I'd get one horn coming on, then both but quietly, then sometimes nothing...they're 40 yrs old, so I decided to buy a new set. I went for PIAA Sport Horns and the difference in volume is like night & day, there are two types the 400HZ-500HZ & the 500HZ-600HZ I went for the 400-500 as the 5-6 sounded to high pitched.

[Jobe72]

It's not the horns themselves, they have been replaced with brand new ones.
Pretty sure it's in the horn button assembly area where I'm having problems.

[srvivor71]

The horns in these trucks are a royal PITA. Here is a thread that will tell you how everything under the horn button is supposed to go. The thread rambles alot but pay attention to LockDoc's postings - he's got it right.
http://67-72chevytrucks.com/vboard/s...+button+convex

All that said, I am back to having horn problems myself - mine won't stop honking. In addition, my brake lights are also not working now. I've heard that brake light problems can originate in the turn signal switch. I also know that the horn circuit passes through the turn signal switch. I have replaced all the other horn button parts, so for thirty something dollars, I am definitely going to try replacing the switch and see if that fixes my problems. Good luck!

[68gmsee]

As Cd said above....

I had a similar problem on mine. I took my horn contact plate out and polished it to a high shine. Then I used steel wool and assorted fine sand paper to polish the contact point on the column.

After I did this, I made sure I had a good grounding system on my truck (imperative) since I had several other electrical problems going on at the time.

I bought four ground straps at local auto parts. (What you want is a good, complete electrical return to negative on the battery post.)

Placed one on bed to frame under the bed.
Cab to the frame. Also under the cab.
Engine to cab. (behind the engine is the stock location)
Installed a strap from radiator support to the negative post on the battery.
Installed new battery cables.

A lot of the electrical components on these trucks relied on frame/cab/engine grounds and years of road grime and rust have diminished the grounding back to negative on the battery.

[cdowns]

if horn relay is clicking it is not a horn button problem

brand new shiny horns dont work if not GROUNDED properly