I have a 1989 Pontiac Firebird 2.8l. I was driving it the other and was stopped at a stop sign waiting for a car to pass. Suddenly the car loses all power and nothing works. I then notice some smoke coming from under hood and remove key from ignition. I look under the hood and I see that the ground wire going to the frame that is connected to the black battery cable and closest to the battery has melted it's insulation and slightly melted the plastic on the battery. So the short happens at the closest ground wire to the battery. Disconnected the negative battery cable and let it sit for the night. Next day when I try to put the cable on the battery I get sparks and some smoke. I checked all the fuses and everything looks ok. Anyone have an idea of where to start looking next? I'm thinking the starter, alternator, or ignition switch might be the next things to check but not sure how to test them. Anyone had a similar issue? Is there something that is more likely than the others to be the issue? Anything else to check?

Also it's important to note that this car has headlights that don't work so the previous owner wired a cable with a switch from the positive post of the battery to the headlights. I have since disconnected that wire but the problem is still there. Thanks.

 

Random guess.... check the rack of relays on the firewall by brake booster. See if wires and connector body look burned or melted, especially the rectangular shaped relays.

I once lost that same small ground wire to battery when one of those relays shorted. It was actually adjacent wires touching each other because the wire insulation shrunk and exposed bare wire at the harness connector to the relay.

 

All those relays seem ok. Nothing burnt out looking.

 

I'd be checking all the power wires and looking for loose grounds.
something is definitely not right.

 

Yeah, the only way to smoke that ground wire is if the B+ wire that shorted to ground was larger (could survive more current). That's a short list of possibilities of wires located in the engine bay & fed from a fusible link. Should be pretty easy to find the culprit.

 

Prob your best first move would be to have a closer look at ^^^^this. If that doesn't turn up anything, next inspect the positive battery cable end-to-end.

 

I had a similar problem and one of the battery cable body mounts on the positive wire to the starter broke and the main cable was shorting to the exhaust pipe. It wasn't hard shorted although yours sounds like it might be.

 

After looking at the car's negative and positive cable up and down, I found that the positive cable was wedged into a metal connector for the power steering. Excessive vibration of this connector caused it to rub through the positive cable and the wire made contact with the metal connector body. After taping that up, the problem went away and everything seems to work fine. It's always something simple. Besides that everything on the negative cable side seems fine. I did find the positive cable on the starter was kind of loose but it wasn't causing issues.

 

This would be a good time to replace/ update the Main Power Connections:

POSITIVE:
-Batt. direct to St. Mot. Sol.
-Batt. to direct to Alt.

NEGATIVE/ GROUND:
-Batt. direct to Engine Block.
-Batt direct to Alt Housing.
-Batt. direct to Chassis.
-Block to Chassis.

 

Would probably use more than tape if it was mine