Gen 2 alternator on a Gen 1?


Active LVC Member
Nov 4, 2016
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Quick question - all of the alternators I can find that fit the 2000 model LS are 110A max output.

The Gen 2 models have a 150A alternator. Does anyone know if a Gen 2 alternator will fit on a Gen 1 model?

The reason I am interested in this is because I put a Gen 2 electric fan on the car in place of the hydraulic fan. It works well, except it draws too much amperage when the car is sitting idle. It’s usually not a problem because I am on the Interstate highway 90% of my commute.
I don't know if it will fit or not physically. Electrically, it is not going to be plug-n-play. The gen I PCM controls the alternator and regulates voltage. The gen II alternator has a built-in regulator. Certainly, the car can be rewired such that the alternator will work correctly, but you may end up with the alternator ("battery") light on much of the time, and maybe even the check engine light.
Yeah... The Gen 1 alternator is lower amps due to the hydraulic fan.

Gen 2 is higher amps due to electric fan. There are places that can rebuild an alternator and put in parts for higher output.

There is a member on here that is making and selling fan controllers for the Gen 1.

Maybe this will help.

Production Gen 2 fan controller for Gen 1 cars

Contact him with any questions.
One suggestion is to consider getting your stock one rebuilt with a higher Amp output?
See if any of the re-builders in your area offer that service.

You did not put what engine you have so I am not sure what's available?
It shouldn't matter, other than the V6 mounting bracket being different (I think), but the V8 being regulated internally is a good thing... If upgraded internal parts are used.
V6 or V8 does not matter as far as regulation scheme goes. (V6 alternator attachment is different than V8 alternator attachment.)

1st Gen : PCM controls alternator.
2nd Gen : Alternator is self controlled.

It's well established that the 1st Gen PCM gets upset if the alternator does not respond to its control signals.
FWIW I did not have good success trying to buy - or build - a high output gen 1 alternator. Bought units failed or caused issues (I suspect they were using the wrong regulator, and I tried 2 or 3 different vendors) and units I built just performed like stock. NAPA alternators were actually the best for me - I would get a minimum of a couple of years out of them and they ran the gen 2 radiator fan just fine. I had quick failures with OReilly and Autozone sourced units. I normally consider all the parts store house brands to be sourced from the same factory, but in this case the Napa stuff was obviously better.
I have a 2005 V6 3.0 Luxury. What size alternator does it have? Also, what size is the factory power wire running to the battery in the back?
IIRC, it's a 4 gauge jumper to the starter, which is 2 gauge back to the trunk. Rated for something like 130 Amps.
gen 2 ls alternator is not internally regulated. the gen 2 s-type is

it has genmon and gencom. field command and monitor signal are a similar strategy to gen 1. go wire it in and try, it’s certainly better than the visteon piece of shit in a gen 1
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