Battery Light and Brake light come on and A/C fan doesn't work

This happens intermittenly, some days yes, some no.

The Brake and battery light will come on, the voltage goes down to 12 (sometimes slightly higher) and the fan for the A/C-Heater won't turn on. The rear Defrost light doesn't come on when the button is pushed, and I noticed just before this started happening that the green indicator light for the A/C button stopped working (even though the A/C still worked.)

I've seen some mention that this is an alternator problem, however it has a new alternator in the car, as well as a new battery. (less than 3k miles on both!) The battery doesn't seem to lose it's charge at all. I have a code reader and nothing new is coming up on that either. (although we do have a problem with the EGR solenoid, but it shouldn't be causing this problem.)

If anyone has run across this issue before and can help, please do. We live in Arizona and really need the A/C!

New alternato! From where?

New from Schucks Auto Supply.

problem is most likely the alternator I personally do not know of any a/m alternators that are worth installing I would check into that maybe someone knows where to get a good quality alt. besides dealer

I've heard the opposite, that the dealer alternators are junk.

well I dont know who you got that info from but they are idiots I doubt you will find any aftermarket alternator that will outlast the one from Isuzu heres an example someone has a 97 Rodeo and the factory alt. finally fails after 6 years of service he replaces it with one from Schmucks Auto supply and has problems with it. I would say that the Isuzu alt. is a better one what do you think

the alternator that was in it wasn't factory... it had been replaced a few times before we bought the vehicle. So I'd say they are all junk.

Your an A$$ Look I have a 1997 that does the same thing. It had a new (AM) alternator in it when i bought itin 1999 which means the factory one gave out in 2 years, replaced with 3 new ones one of which was from a dealer, guess what same problem. The dealer told me there are tons of similar probelms that are "Electrical hiccups" that cuase this particular problem.

Now what you may want to check is that the power cabel going to alternator isnt shorted, and that the body of the truck isnt sutting a wire, mine turnred out to be several wiring defects in dash and off the main limes from battery to the alternator.

Now unless you are the owner of isuzu and the make of the alternator dont go spewing info like your God.

Nuff siad.

that was I think one of the confusing post Ive ever read that or you just proved someone did not know what they were doing
was the first, I mean original alternator really bad or was it a misdiagnosis I have a 96 troopper with nearly 300,000 miles on it and it still has the original alt. and I see many of these vehicles with well over 100,000 miles on them with original alternators yet every now and then someone will come in and say that there having problems starting the vehicle they always have to jump start them followed by I just replaced my alternator it is always an aftermarket job under the hood I am not saying that there arent any good a/m alteernators only that if you are going to use one do a little research you may find on that is more reliable than the dealers but those are te ones that I knoand deal with so as far as calling me an A$$ I belive it was really inapropriate I was only trying to help you but after everyone reads your post I hope that nobody ever helps you D/A

I have this exact same problem with my 97 rodeo.

I replaced the alternator because the mechanic said it was the alternator and 400.00 dollars later……..same thing …so I called the mechanic back and he again said it was a bad alternator and replaced it again ( for free this time ) and guess what ….same f**k problem again .. I am at a lost …don’t know were to go or do now … the funny thing about this is that when I accelerate the voltage meter drops from 14 volts to 12 volts and the heater fan speeds down slow, when I release the acceleration, the voltage meter goes to 14 ( normal ) and the fan goes back to normal speed.

Here is the catch….when I turn my head lights on????? No problems everything works normal….. no voltage drops, no fan problems , nothing !!!!

If I run the car ( without the head lights on ) for an hour or so, my battery light, the 4x4 light , and the break lights go on ( on the dashboard ) and of course the heater/ac fan speed slows down….. Then everything will go away as soon as I turn the head lights on…

Please help if you can ….I’m lost !!!!

from what you are describing everything is working as it should be but just in case you may want to check grounds to be sure they are clean and secure

I have this exact same problem with my 97 rodeo.

I replaced the alternator because the mechanic said it was the alternator and 400.00 dollars later……..same thing …so I called the mechanic back and he again said it was a bad alternator and replaced it again ( for free this time ) and guess what ….same f**k problem again .. I am at a lost …don’t know were to go or do now … the funny thing about this is that when I accelerate the voltage meter drops from 14 volts to 12 volts and the heater fan speeds down slow, when I release the acceleration, the voltage meter goes to 14 ( normal ) and the fan goes back to normal speed.

Here is the catch….when I turn my head lights on????? No problems everything works normal….. no voltage drops, no fan problems , nothing !!!!



I got the same problem on my 96 Trooper 3.2 V6, only it doesn't matter what I turn on or off. The problem started when a shop welded on the exhaust system. The problem depens on the temperature. if it is hotter it happens more.
Question, if you add throttle really slowly, does the problem still exist? With mine it doesn't do it if I advance the throttle slowly.
I had that checked out at an Isuzu dealer, but they could not get any useful info to me. I installed a new alternator, did not help, cleaned a bunch of ground wiring contacts in the engine compartment, did not help.
Anyway, if I will find anyting that helps, I will let you know.
Andy

I have an 94 Infiniti G20 that is having the same issue, and a couple people were telling me that it could have something to do with the ac condenser. I dont know much about that. Also I heard that it could have something to do with the fuse.

Well, this is an Isuzu Rodeo forum. Not many people here are going to be intimately familiar with an Infiniti G20. Also, this thread is almost 6 years old. Reviving long dead threads is generally frowned upon.

if your alternator has a 4 pin connector vs 3 pins (I think these started on the 3.2L engines, sometime in 96), you also have a PCM control wire that de-excites the alternator when you stomp on the gas. When this happens, it drops the charging voltage down from the normal 14.5 V or so to just 0.2 V - 0.3 V over the battery voltage. When you let off the gas, it goes back up to the normal charging voltage.

Suppose to make the vehicle more fuel efficient.....