First real post on the site and hate it is a ? but I have an elec. prob I cant find
I have a 66 conv 289 w/3 sp man. that I only drive on nice days with the top down. Its grandpa's car from new that I have kept as original as i can. Enough of that.
After being cooped up all winter I go out to change the oil and coolant, fire it up, let it run 10 min or so to check out the thermostat and look for leaks, take it for a 20 mile drive.
What the prob is: So the battery is dead (an Optima), no surprise right. Well every two years or so I find that when I recharge the battery and install it sparks when I touch the pos to the post. I go through the car looking for anything that could be still on, lights - bla bla. What I normally find is the horn is stuck on. Or in the middle of the night mid winter the horn will just come on and scare everyone to death. Yes I have changed the contactors under the steering wheel (5 times now) and that fixes it for the next 2 years. But it happens too often and I just dont get this. I have multimeter s but the thing is I DONT REALLY KNOW HOW TO USE THEM. OK, dont laugh, I work on cars pretty well, but electrical stuff is like spelling to me and unlike spelling the car doesnt have spell check.
I know the 42 year old wiring has something to do with this but it really seems like there is something in the steering column that is worn out that should be replaced but I dont know what.
The temps are supposed to be in the mid 70s this weekend and I would love to start driving it again.
Sounds like you certainly have a voltage drain somewhere, and since the horn acts up, that could be a good place to start. When I was putting my '66 convertible back together I had the contacts all screwy, and I kept hearing a clicking sound from the dash. Turns out the headlight switch was shorting out. Go figure. Fixed the horn and now the switch is fine. It has led me to mistrust my car with its own battery, so when I am finished driving it for the day, I flip the battery disconnect.
Here is a site that has great Mustang wiring diagrams, they should help you get started:
As a starting point, you can connect a test lamp between your + battery post and the cable end. It will light up if you have a drain, which you do. Start pulling fuses one by one until the light goes out, you might get lucky. On the circuit it goes out on, that's the place to start looking. Be thorough and check all circuits, you may have more than one draining. Not all of your Mustang's circuits are fuse protected, but it is a good place to start.
Michael
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1966 289-2V C-4 Convertible. All original drivetrain. Factory center console and power top. Dual res. MC and power brake upgrade. Rust bucket brought back to life, I am the 2nd owner of "Lucy".
1990 GT 25th Anniversary 5.0 AOD Convertible. Dynomax cat-back, K&N, the usual crap. Welded in subframes, welded in reinforcement plates (Ford riveted them in. Go Ford! )New engine and transmission. Date coded radiator hoses. Second owner of "Katie".
Thanks, I will start there. For such a simple car this wiring baffles me.
Just to also say, I pulled the wires off of the horns them selfs, just to see what would happen. No surprise that it "fixed" the drain and when I plug them back the drain starts again.
I am going to start with your suggestion.
Thanks again.
The horn circuit and the Amp gauge (if equipped) are the only two things that aren't protected by a fuse. You have a short to ground on the hot side of the horn circuit. If there was a problem on the ground side, the horns would be sounding. Since this horn circuit isn't fused, it keeps draining the battery. Look at the wires for melted insulation and, I believe, the 66 has a horn relay. The 67, I know, doesn't have one. It was taken out of the circuit and full horn current is run through the contacts in the button.
The reason that you are going through so many horn buttons may be because someone has bypassed the relay (the relay is supposed to carry the high current to the horns and the horn switch carries a low current to activate the relay). The current is too high for your horn switch to survive if the car is supposed to have a relay. The contacts will burn up.
The 64s did, and maybe the 65s? High current is passed through the horn button on the steering wheel. Of course with all Mustangs, you never know what ya might find under the hood.
Now that you mention that Greek, maybe the horns will be my next relay project.
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1966 289-2V C-4 Convertible. All original drivetrain. Factory center console and power top. Dual res. MC and power brake upgrade. Rust bucket brought back to life, I am the 2nd owner of "Lucy".
1990 GT 25th Anniversary 5.0 AOD Convertible. Dynomax cat-back, K&N, the usual crap. Welded in subframes, welded in reinforcement plates (Ford riveted them in. Go Ford! )New engine and transmission. Date coded radiator hoses. Second owner of "Katie".
First real post on the site and hate it is a ? but I have an elec. prob I cant find 
)New engine and transmission. Date coded radiator hoses. Second owner of "Katie".
