battery light on after positive/neg switched

0007 · 12-28-2007, 08:14 PM

did a very dumb thing, while installing a new battery the posi/neg terminals were in oppisite sides than usual so I accidently hooked them up wrong for a quick moment. So now the battery light is on. I was told the alternator was bad so I replaced that. Then exchanged the battery. I checked every viewable fuse under the dash and under the hood. 2 under the hood were fried but thats it. Since the issue the gauge cluster and radio lights are dimmer than usual and I notice a difference in the drive. It seems like the shifting is different. If anyone has an idea of what else to check please lmk, thanx

ABE · 12-29-2007, 07:53 AM

There is often a very large fuse in the circuit for the alternator. The heavy wire from alternator to pos battery connection usually enters a power distribution box where there is a 175 amp fuse. Connecting the battery up backwards will blow that fuse and the alternator light will be on because the alternator is not getting battery voltage and therefore cannot generate a current flow. Check the voltage at the alternator with engine off and it will be zero, open circuit. Check the wire out of the box to the battery and it will be 12 volts.

Ford calls the fuse the Megafuse and this name appears on the access panel to the power distribution box.

All you need to do is replace that fuse at the end of the box where battery and alternator wires converge and the car will run properly.

0007 · 12-30-2007, 09:34 PM

Thanx man, you were exactly right. I actually found out yesterday. Pulled out the meter and by chance checked those 2 fusses and sue enough. But again thanx for your help.

ABE · 12-31-2007, 02:00 PM

Quote:

Originally Posted by 0007

Thanx man, you were exactly right. I actually found out yesterday. Pulled out the meter and by chance checked those 2 fusses and sue enough. But again thanx for your help.

Thank you for letting us know the solution to your problem. Big help to everyone.

Flyingjackal456 · 01-01-2008, 02:31 PM

Whenever you pull out the battery, the computer resets. Meaning shifting, fuel/air mixture, and other things like that are reset to factory specs. The computer will "learn" how you drive shortly and you'll be on your way.

Glad you fixed it, just letting you know why the car may feel different.