My step dad and I are working on an 86 pontiac Fiero gt. We had to move it and when running, a long brown wire that ran from the positive terminal to a black box on the right side of the trunk, got caught in the belt and was yanked tight and the car shut off. We cut the wire and took off the excess wire that was caught, then used and electricians wire cap to screw the two pieces back together. Now the power in my car won't go on unless the ground wire from the negative terminal is touching metal and when I touch it to metal it sparks. What's going on? Please help

Previously, that negative ground wire did not have to be connected to anything not to my knowledge, but what is the ground wire coming off of the negative terminal supposed to connect to?

I took apart the black box and that didn't help. It was the positive terminal that got yanked and now the power only works when the detached ground wire from the negative terminal is touching the chassis and it sparks. It doesn't make sense

Additional Details
the positive terminal has two wires coming from it, one goes to the starter solenoid, the other does go to the junction box. but before the wire that was going to the junction box got yanked, there was no problem. i checked the junction box and did not see any loose wires. the negative terminal also has two wires coming from it which from the wiring diagram i have, says they are both ground wires. one wire is larger than the other however and goes somewhere behind the motor but i cannot see it. i will have to check. the other wire coming from the negative wire however is relatively short, small and to my knowledge, has never been attached to anything although the end of the wire is a ring that looks like it should be bolted down. it never sparked before so idk what is wrong . now that i think of it, i should replace the yanked wire , i am planning on replacing the entire positive terminal wiring and eventually the negative as well to see if the problem is fixed but i just have no idea

When you ground the negative wire does it spark a little bit and then the lights come on? Or does it spark like it is a dead short with a loud pop?

If it grounds with a large pop, then you have to figure out what is shorted to ground

If it grounds with a little spark and the lights come on, then your problem(s) are all with the grounding. The negative battery cable needs to run to a good ground on the engine. Stock that was up on the exhaust manifold. It does not have to remain there, however it MUST remain on the engine. Replace your battery negative cable and make sure it is bolted to a good clean connection on the engine. Then inspect the engine to body ground wires and add a second one.

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