I have a 97 Grand Caravan, 200K+, 3.3L. Yesterday the battery light came on. I discovered that it comes on when I have the defogger on for a long time. When I turn the defogger off, the light goes out after a few minutes. Also, when I start it up, it is not on. I went to Autozone to have it checked out and it came up as having a bad diode and was putting out 89.4 amps and the battery light was not on. My question though, is can I replace this with a 120 amp alternator? I think that I have a 90 amper since I do not have the rear heater stuff. I'd appreciate any replies. Thanks!

 

Sure you can, the 120 amp alternator will give 98 amps where the other one gives you only 86 amps.

 

Thanks for the reply. So does that mean that I have a 120 amper? The measured amps at Autozone was 89.4 - which is lower than 98, but higher than 86. I havent measured the casing, which is the other way to determine the amps.

 

That means the 120 amp alternator puts out 98 ampere and the 90 amp puts out 86 ampere.