Horn honking on hood close and big bumps

[mrmolding]

Checked and double checked grounds but each time I close my hood or go over a decent bump, the beep beep horn goes off. It’s a 70 road runner with all new wiring and an repop horn I got from year one.
Just driving me nuts since I’ve gotten just about all of the bugs out of the car.
Another really strange thing the car does is if the car is under load (accelerating) and I beep the horn more than once, the aftermarket radio cuts out. It’s a newer alpine with ignition connected to original radio connector and battery memory connected to the back of the lighter fuse spade.
Any thoughts or what I can check?

 

[pnora]

Unplug the radio and see what it does.

 

[mrmolding]

Unplug the radio and see what it does.

Tried that first. Horn still honks when hood closes or bumps. Crummy repo horn? Bad horn relay?

 

[pnora]

Tried that first. Horn still honks when hood closes or bumps. Crummy repo horn? Bad horn relay?

Will not be the horn. Something is telling it to beep. Could be something in the relay. Ground completes the circuit. So if the ground wire is rubbed through some where it could cause it. I would start at the steering column connector and take the wire out and drive it. If it does not beep you know its in the column. At least try that and see where it takes you.

 

[mrmolding]

Will not be the horn. Something is telling it to beep. Could be something in the relay. Ground completes the circuit. So if the ground wire is rubbed through some where it could cause it. I would start at the steering column connector and take the wire out and drive it. If it does not beep you know its in the column. At least try that and see where it takes you.

Awesome! Thanks! I’ll give that a try!

 

[Rusty knuckles]

You say new wiring but something I think is worn through and grounding out somewhere. Had a similar thing on my 69 charger years ago. Opened the hood at the gas station while filling and when I closed it horn took off like crazy. Found the wore had just barely laid against the alternator pulley and was shorting out.

 

[snakeoil24]

Relay spring could be bad

 

[mrmolding]

Thanks everyone! Went out and checked obvious things again. When I closed hood the friggin horn went off again. Just kind of shudders not like a full beep. Going to start taking things apart tomorrow.

 

[khryslerkid]

Bad relay.

 

[mrmolding]

Bad relay.

Bought it new a few years ago. Am I better off with a nos one or are older ones a gamble? Thanks!

 

[mrmolding]

Ok, so I took out the new relay that I got when I replaced the harness. I then put back in the original relay that looks to be the one that came with the car and no beep when hood closes. Amazing! Really disappointing that for 40 bucks I get junk and a 50 year old part works. First two pics are the newer one and last two are oem. You can see that the terminals in the new one are farther apart than oem.
Thanks again everyone! I won’t test drive until tomorrow but seems to be much better.

 

[eldubb440]

I'll run a good old part over new junk any day

 

[mrmolding]

I wanted to update my findings on my horn beeping and stereo cutout issues:
1. Horn relay as I mentioned above fixed the horn causing stereo to turn off and on again. I got a nors one vs original oem reinstalled in last update and is fine.
2. The horn honking on hood closing and big bumps turned out to be the wrong horn switch. There are two switches based on the type of horn ring or pad and one is really easy to compress and the other is harder to compress. I got a new horn pad and it came with the easier to compress switch 2822126. Turns out that I needed the 2771534 that is more stiff and can handle a heavy horn pad/ring.
Glad it wasn’t anything more serious and makes sense as to why pad would cause the 2822126 to go off with bumps. Thanks again for all of the help!