1977 horn problem It don't work

[Mark A.]

How's that for a title! The horn is inoperative on the 77 Bubba mobile I'm presently working on. The horn relay is not on the left inner fender........ so could someone tell me where it is mounted, so I can start to trace things out. My wiring diagram in the 68-82 service manual shows the relay mounted on the inner fender. Any help from someone who has worked on these 77's horns would be appreciated. Thanks, Mark

[Tom R.]

Re: 1977 horn problem It don't work

Well you know sometime in 77 the switch was moved from the fender to the driver's side door lock mechanism. My guess is that if it was located there prior to the move of the switch, the relay would have been moved as well but the relay is under the dash in 1978-82. In 1978, the horn relay is in the harness above the fuse panel. The diagram shows the stop/haz fuse routes to the relay and onto the horns.

[Mark A.]

Re: 1977 horn problem It don't work

Well you know sometime in 77 the switch was moved from the fender to the driver's side door lock mechanism. My guess is that if it was located there prior to the move of the switch, the relay would have been moved as well but the relay is under the dash in 1978-82. In 1978, the horn relay is in the harness above the fuse panel. The diagram shows the stop/haz fuse routes to the relay and onto the horns.

Tom,
I think I found the relay. It has 3 terminals with a blue plastic cover? The large red wire to it has power. I bench tested the relay, and with power to the coil, it pulls in. When you push in the horn button, there is no power to the horns. Problem in the steering column or??? Any help would be appreciated. Thanks, Mark

[Alan D.]

Re: 1977 horn problem It don't work

Mark,
The horn relay on a 1977 is located above the fuse panel on the drivers side. It is a plug in connection. Have fun.

[William C.]

Re: 1977 horn problem It don't work

You should have power coming up the column, the Horn button supplies a ground connection. A quick check at the horn switch should tell you if the problem is bower to the column, or lack of grounding when the switch is closed. If the car has set for a while, corrosion in the switch under the horn button is not an unknown occurance.

[Mark A.]

Re: 1977 horn problem It don't work

Okay I found the relay. I have jumped the black switching lead to ground and the horns work. So the problem is between the relay and the column. I want to find out if it is in the wiring from the connector on the column to the relay, or in the column. Is there anywhere that I can download the 77 wiring diagram online? Or can someone tell me what terminal is the black switching wire at the column connector? Mark

[William C.]

Re: 1977 horn problem It don't work

Do you have the service manual? I believe the wiring diagram is in the service manual. I don't have one for that year.

[Edward J.]

Re: 1977 horn problem It don't work

Mark, if you just take a test light and touch the wire harness connecter coming out of the lower steering column the horn will blow when you touch the right wire connector, Not sure of the wire color but ground the test lamp and just touch each wire until you heat it blow. this will tell you if its up inside the column. Which it likely is. What I have seen is there a spring loaded contact that will sometimes the spring fails because of heat then the spring looses it ability to stay in contact with the horn button. removing the button will show you if its a problem.

[Mark A.]

Re: 1977 horn problem It don't work

I looked at a 80-82 diagram, and the relay and wire colors were the same. So I was able to find the wire. I replaced the wire from the connector to the relay, and now the horn is on all the time. Obviously someone cut the switch wire under the dash, because of this problem. So the real problem is in the column. Somewhere in there, it is touching ground all the time. Is it difficult to remove the top portion on a tilt-tele column? I have rebuilt my straight columns, but not these. Mark

[Alan D.]

Re: 1977 horn problem It don't work

Mark,
Working on the top part of the 77 steering column is pretty straight forward. You will have to take the steering wheel of to get to the contact inside, but all else is pretty easy. Just be patient and organized and you should be okay.

[William F.]

Re: 1977 horn problem It don't work

Had horn blowing all the time in a C1. Problem was a short/continuous ground inside column where paint around column where bearing inserts had worn off giving undesired path to ground. Would have to look inside your column to see if same design.

[Jim S.]

Re: 1977 horn problem It don't work

This paper should get you to the point where the T&T turn signal switch can be partially pulled from the turn signal switch housing. That should allow you to inspect the wiring for obvious ground problems. I would also check the upper horn contact for evidence that Bubba may have caused it to permanently ground the horn relay.

http://jimshea.corvettefaq.com/wp-content/uploads/2012/05/TTColumnDR1Rev25FE20122.pdf

If your T&T column has not been disturbed for many years, you will most likely find that the the c-clip retainer breaks into many pieces when you try to remove it.

The retainer is no longer available through GM dealers #7808385 but is still available through most Corvette suppliers such as;
Zip SC-517
Willcox 780838
This paper (in Microsoft Word format) trouble shoots the horn system. The schematic should be quite useful.

http://jimshea.corvettefaq.com/?p=909

The black wire (position G) in the harmonica connector is the horn.
This pic should be helpful as well.

http://jimshea.corvettefaq.com/?p=909

Jim