Chumley

I just picked up a '72 Cutlass supreme a couple of weeks ago. Some of the wiring is a mess. The positive battery cable had a piece spliced on near the post, apparently a quick fix at some time. I went to start the engine after sitting about a week. The engine cranked kind of slow, like a Mopar, but usually would start. After about 2 minutes trying to start it, it sounded like it backfired through carb, and I noticed a little smoke come up through hood on battery side. I opened the hood and could smell hot wire. The positive cable was way hot, though not burning. I disconnected it, and heard some sizzling inside the battery. Today I pulled the positive cable, and it had a 12 gauge wire spliced into it at the solenoid terminal which went up to a relay on the firewall near the distributor, which had several other wires attached to it. Since I've had the car, the alternator light stays on, which it did previous to my acquiring the car. I noticed there is no wire connecting the alternator to the battery. Should this not be the case? I have a '72 Chevy truck and the positive cable has a 12 gauge wire going to the alternator. I do fairly well with wiring diagrams, but I just wanted to find out how that positive cable should be. An HEI distributor (GM) was also put in, so I know that's why the yellow resistor wire is cut off and just hanging. I'm probably going to have to replace the harnesses eventually, but I need this thing drivable in the meantime. Any input appreciated..................Chumley

texasred

Chumley,

The alternator connects to the battery through the horn relay on the firewall.

C.J.

Oldsguy

You should re-wire your primary circuit. New cable from the battery to the alternator via the relay C.J. metioned. New cable from the relay to the starter. New wiring wherever you find a splice or "mickey mouse" setup. That is why you got the overheated wiring problem and smoke, poor connections caused excessive resistance in the circuit which cause the heat. Bad, bad, bad. If you don't fix it you are asking for a fire. Oh, and a new battery too.

Chumley

Thanks for the quick reply guys. So that little oblong shaped relay on the fire wall is the horn relay? Is this correct for the positive cable, a smaller gauge red wire branching off from the terminal end of the solenoid going up to the relay? I don't know how this setup lasted so long with the previous owner. Any ideas on why the alternator light stays on after engine is running? Is that attributed to the fried wiring and or battery? The battery was made in 2003 and is 84 month, but the car had been sitting a lot without engine being run. Thanks...........Chumley

Oldsguy

You said your battery was "sizzling", that was probably because you had a bad cell in the battery, or maybe more than one. Battery lifetime dates are for general maintenance scheduling, if you have had trouble with your primary electrical circuit I just figured you would be better off and safer to replace it. I guess you could have the battery analyzed under a load at a service place but bear in mind if they find anything slightly abnormal their recommendation will be for you to replace it since their business it to sell you something . As for the smaller red wire from the solenoid to the relay, if you mean from the starter solenoid then you are right. That is ACTUALLY from the relay to the solenoid. That electrical tie point routes Battery B+ from the battery positive terminal to the starter solenoid when you turn the key, there is another wire which comes from the ignition key to the solenoid which actually causes that to happen. Then also, there is an electrical tie point from the B+ to the starter motor itself and that wire should be as large as the battery cable from the positive terminal from the battery, they should both be attached to a terminal (stud or bolt, held on with a nut) on the relay. At least that is the way a basic primary circuit is wired on most cars. The B+ is always present at the starter motor and the other side of the starter motor winding is grounded when the solenoid engages the starter motor. That is the click you normally hear when the starter motor is bad, I am sure you have heard that before, the solenoid actuallly moving makes the clicking sound. If the starter motor works too then you never normally hear that because the engine starts almost immediately. I hope this helps you out and I hope I explained it well enough. Good luck.

Chumley

Thanks, I get most of it. When you use the term relay, I assume you mean the horn relay on the firewall. I didn't realize all the starting circuit ran through the horn relay. I do plan on getting a new battery as well as new cables, and eventually a new engine harness. Electrical is one of my weaker subjects, but I'm slowly learning. Thanks for the help.......Chumley

Oldsguy

I don't think C.J. meant the horn relay but will wait for his reply. I was thinking about the starter relay (which happens to be on the fender of my Delta).

texasred

Actually, it IS the horn relay. I don't know about Deltas. On 70-71 Cutlaii (plural of Cutlass?), the relay was on the fender but moved to the firewall in 72. It is wired like a power take-off. The main battery wire goes to the starter and a second wire runs to the horn relay. Other than the starter itself, EVERYTHING on the car runs from the horn relay.

C.J.

Oldsguy

Thanks, probably the same on my Delta, I never thought about what Olds called it. I knew what it does as far as the ignition goes, just always thought it was the starter relay...