Q: Solving electrical problem resulting from reversed battery terminals

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I bought a replacement battery for my 1999 Nissan Frontier (2.4L), but was given the wrong model. It appeared identical to the previous battery, but the positive/negative terminals were reversed.

In a hurry to install it, I stupidly set the clamps on the terminals which, of course, caused sparking, and blew the fusible link.

I got the correct battery and replaced the fusible link, along with the positive clamp, which had a small crack in it.

Still, with the positive clamp tightened, touching the negative clamp to the battery post results in excessive sparking.

What is the best means of tracking down the short? Remove fuses one at a time and use a test light on the circuits?

Is there a "best place to start" with this model vehicle? I have access to wiring diagrams in my Haynes manual.

Thank you very much for your time and attention. It is greatly appreciated.

Best regards,


My car has 110000 miles.
My car has an automatic transmission.

Reverse polarity, at the battery, in a 12 volt electrical system on a car can cause a variety of effects including damaging the alternator, diodes and the numerous microprocessors on a vehicle like those in the powertrain control module (PCM). If you have successfully started and run the car, all accessories work, and charging system output is normal, that’s a good sign and you are lucky. As far as the sparking, there is always current draw from a car battery to some circuits in the vehicle’s electrical system, even when the vehicle is off, so when you re-attach a battery there can be some sparks. To determine if the current draw when the vehicle is off is excessive, a Mechanic would use an ammeter and measure the current flow from the battery to the vehicle’s electrical system. Typically, you will find perhaps 20 to 50 milliamps of flow. If the current flow exceeds that, you simply test each major branch circuit to see where the "excess" is and then troubleshoot the individual circuits and devices on individual circuits until you find the fault. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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