I just replaced my manual trans and when I was hooking everything up I went to go attach my battery connections. I had the body ground hooked up and went to go attach the engine ground to the negative post, but it slipped and accidentally arced on the positive post. I had smoke coming from the arc and back of my engine. Car has no power at all.

The dome light doesn't come on when the door is opened. I know all my connections are good and my ground for the starter is attached to the trans. What could my issue be? I'm hoping it's a relay or a fuse, not that I fried an ECM. But that being said. The car would still have power right?

Any help would be greatly appreciated. I'm a mechanic myself and I have certifications. But not in electrical yet. I just want to trace my problem down so I can fix it and get her up and running.

  • 2
    "I'm a mechanic myself" I wouldn't announce that, at the moment. (Joke… we've all been there) Check the fuses.
    – justinm410
    Commented Apr 5, 2017 at 4:53
  • 1
    I did. They're all fine. I've checked some of the big j case fuses. They're all fine. Relays that deal with power and ecm. Those have no issues either. I've yet to check the dash fuse block. But the underhood fuses are fine Commented Apr 5, 2017 at 11:18
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    Check the fusible link with a multi-meter. Sometimes you can not see that it is burned (blown). It is designed to protect the electrical system in cases just like this.
    – CharlieRB
    Commented Apr 5, 2017 at 11:56
  • Are you sure there isn't a main 12V fuse? I wouldn't be surprised to see a single fuse that protects the battery itself from an overcurrent (read: arc short) situation.
    – Hari
    Commented Apr 5, 2017 at 17:30
  • Which fusible link would it be? I checked the 100amp main fuse and its fine. I don't know if there's a main 12v fuse or where it would even be located at Commented Apr 6, 2017 at 4:13

2 Answers 2


Think about what you have done. You connected one ground connection to negative terminal and another to positive terminal. This way all the current traveled through those wires and body of your car. So, it should not have gone through any fuses or ECM. One of the ground wires connect behind firewall, so that was probably what made the smoke

The easiest way to tests connections would be using a multimeter (or continuity checker).

My first thought would be checking the ground connection. Remove both negative connections. Set multimeter to continuity checking mode and then test both wires separately. I would also test that ground is connected till dome light by testing dome light negative write.

My guess would be that the problem is related to negative connections but if you rule them out, you can make similar test to positive connections. If something else happened than that you described, it may have burned main fuses. Start checking continuity in the engine bay fusebox then the one inside.

The reason I suggested to check dome light was because it is just a simple thing to check easily, if you knew that bulb is not burned and it was working fine before.


Did you confirm the battery still has a charge? Check the ground braids. When you shorted the battery, you may have melted the ground braid. There is usually one from the engine to the body. Some vehicles also have a fusible link on the ground side of the circuit.

  • Battery was brand new. Has 12.5 volts. Tested after the accidental arc. Now would there also be fusible links on the positive side of the circuit? Or on the ecm possibly. I haven't pulled the ecm. But I've contemplated it just to see. It's not in a hard spot to get to. Just under the drivers side of the dash. Power dist center didn't have a fusible link beneath it so I've ruled that out. Starter tested out fine so I have to put her back in and trace the problem now. Would the fusible links be in the actual wire loom beneath the conduit? Commented Apr 12, 2017 at 5:49

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