I'm having a couple minor electrical issues with my '79 Catalina that I'm having a hard time solving. The first, is the horn doesn't honk when you press the two buttons. The fuse seems okay, I replaced it with a new one to make sure, and that didn't fix it. I was going to check the voltage at the horn with my voltmeter, but I'm having a hard time finding it, haha. Where is the horn?
The other somewhat significant issue I'm having is the radio doesn't work. The horn and radio are on separate fuses. The original head unit was replaced with a more modern one that includes a CD Player. I'm told the stereo worked before it was parked 4 years ago. No significant water intrusion has occurred with the vehicle. The passenger door seal leaks a bit and makes a wet spot in the front passenger carpet, well away from anything electronic. The underlying floor pan isn't rusting.
The last thing should be pretty easy. How do you change the turn signal indicator bulbs in the instrument panel? Does the whole panel need to be pulled like in a newer car, or are they accessible from behind the knee panel above your legs?
I have not worked on that particular dashboard but I'm pretty sure that to change instrument panel bulbs you have to reach up behind the dash from underneath and feel for the bulb holders. (That's the case on other cars of the vintage I have worked on.) If the panel can easily come out from the front it might be simpler but you may have to reach behind and disconnect the speedometer cable first. Be aware that GM designers typically hide razor blades behind the instrument panel to catch the unwary while they feel around for the bulb holders.
The horn could be the switches in the steering wheel, the wiring or contacts in the steering column, the horn relay, or the horn itself. Basically you need to trace out the circuit with a test light or voltmeter.
If the radio is completely dead (no lights, no sound) I'd first check to see if it's getting power. Depending on how good an installation job was done, wiring could have come loose.
I'll see if I can get that knee panel out and get my hands up in there. I'll also check out the contacts inside the steering wheel, if I can figure out how to get the center cover off. Where is the relay for the horn? I've checked out a fuse diagram for the car and they don't indicate a relay exists for that circuit.
All I can say is that on cars that age the relay is usually under the hood somewhere. There pretty much has to be one since the steering wheel setup wouldn't be able to handle the current alone. It should look something like this:
I Googled the horn relay so I can see what it looks like, since no fuse diagrams showed it. I thought that might help locate it after I see what it looks like. I found it, it was under the dashboard. There doesn't seem to be anything wrong with it, but it's a box with plug ends. It's bright yellow and has no identifying markings, so I'm assuming it's a cheap knock-off and am gonna get an AC Delco from AutoZone. Hopefully that fixes it. I disassembled the horn pad. The metal is all fine in there. I wish cars were so simple nowadays, haha.
Before you get too deep it might be a good idea to test the horn by briefly hot-wiring it to the battery. That needs to work before anything else is going to do any good.
Use care if you do that, the horn pulls a fair amount of current and you don't want to create a spark at the battery terminal. Connect your test lead to the battery first, then touch it to the horn's electrical connection.
the horn is usually at the front of the engine bay
