Hi, the horn relay in my 68 Delta 88 is draining the battery, As soon as I disconnect the wire that goes to the battery it stops draining, but then the car won't start. I looked at the manual and it is hooked up correctly so I replaced it, but it is still draining. My plan is to run the wire to a switched source so it only has power when the key is on, but I'm afraid it is fairly high amp draw and will just blow whatever fuse I hook it to. Is there an easy way to hook it to the ignition switch without going to the fusebox? Like maybe something under the hood? Otherwise how can I find out what is causing it to drain? Thanks.

 

So does the horn itself work right?
If so, then the horn relay is not the problem.
That big stud just serves as a junction block to distribute power. Next step would be to put a current meter inline with the battery - and the - cable and see what you read. Key stays OFF during this test. Then start pulling fuses one by one until the current draw goes away. You might disconnect the regulator and alternator before the fuses to see if the issue is there.

 

Yes the horn works, I will check the fuses.

 

I pulled all of the fuses and none of them stopped it. When I unplug the little plug in the back of the alternator, the drain stops.

 

I had a similar problem with my internally regulated alternator, turned out to be a screw that wasn't isolated from the alternator casing properly.

 

So is your alt the original type with ext reg or something aftermarket?

 

Is the problem the horn relay or the alternator? I'm confused.

- Eric

 

It is the original type. I just remembered that it does not have a ground wire on it, I wonder if that is causing it, I will have to check that out tomorrow.

 

The alt does not have a ground wire - it grounds through the case.
It is possible one of the diodes inside the alt have turned leaky. They can replaced after the alt is opened up. With key off, and plug plugged in, measure from the white wire to ground with a volt meter. If you get something, the diodes leak.

 

The horn relay does not have a ground wire. It grounds to the body.

In a '68, if I recall, there is no ignition key buzzer, so the relay has four terminals.
One is the ground.
One is the hot post to the battery.
One is the wire from the relay to the horn button, which is grounded when you blow the horn.
One is the wire to the horns.

That's it.

Press horn button —> ground horn button wire —> current flows from battery post through relay coil to ground, pulling contacts in and connecting battery post to wire to horns —> horns blow.

That's all there is.

No rocket science or magic.

- Eric

 

He found the issue was with the alt.

 

Okay, I've got it now.

He replaced his horn relay because disconnecting the alternator (the wire to the battery) from the horn relay stopped the battery from draining.

Kind of like replacing the fuel pump because you've got a bad float needle.

Why do people replace parts first and troubleshoot later?

I think I'm in a bad mood.

- Eric

 

So the horn relay has needs to have two red wires one to the batterry and the other to the Alternator?? Im havin the same problem

 

Hey! I'M supposed to be the cranky curmudgeon on this site!

 

Depends on the car and year.
On the horn relay in 72 -
One to the ALT, one to the regulator, one to the starter solenoid (where the + batt cable connects), one to the fuse box inside, one to the AC blower relay and one to the rear defroster (if you have it).

Two's of them's a crowd......

 

Always room for more cranky old goats!

 

I defer to your crankiness, Joe, as it is made of sterner stuff than mine.

- Eric

 

I will have to try that, I haven't gotten a chance yet because now I have much worse problems... https://classicoldsmobile.com/forums...tml#post485717