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Date: 2003, Apr 17
Author: Tad G

By: Dave

GM 180Amp High output Alternator conversion from stock Hitachi 60/70Amp on Isuzu 3.2L SOHC

I've had serious Alternator problems in the past. Most coming from a short in the Alt/Battery Harness (It's a crapy design on the 3.2 SOHC). Matt at Independent 4X hooked me up with a friend of his that converted his stock Alt to a GM H/O alt 180Amp. On his Rodeo 3.2 SOHC.

Doug Brown was the guy that originally did this. Thanks Doug, Ill toss some pics of your rig in this.

Well After talking to him I decided to go for it, this would eliminate the factory wiring harness for the battery and deliver more charging power for my lights/winch when I get the added down the road.

I'm going to try and detail this as much as possible without being too long.

I ordered the Alternator from Alterstart: http://www.4alterstart.com/ They are in TX the cost was roughly $129 The new Harness was $9 or so and $16 in shipping to Florida.

Here is the Alternator: 3 different shots it is slightly larger than the stock Alternator, but the biggest difference is the exterior cooling fan.

newalt1-hi.jpg

newalt2-hi.jpg

newalt3-hi.jpg


You will notice the 2 wire pigtail included as well as the spacers and additional pulley. The spacers and additional pulley will need to be changed and positioned level with the drive pulley. The new alt pulley sits back slightly so without the spacers the belt will rub against the engine. I used 3 spacers to make the distance of drive pulley and Alt pulley level with each other.

There are three small bolts on the back of the Alternator, these need to be removed and reposition the back so the pigtail harness sits at the 12 o'clock position when mounted. It makes getting to the power out bolt tight, but doable. Best suggestion would be to attach your new 4gauge battery wire before you tighten every thing down. Took me 10 minutes and some bruised knuckles to attach and tighten it down after installed.

The outside harness clip is just cut off and the wires stripped. These will attach to the old harness wires after you strip them down as well. You have 3 wires connecting to the old Alternator 2 keyed and 1 hot. The two keyed attach to the yellow, the hot attaches to the red. Ill get more into that later.

Here is the stock Hitachi Alternator mounted in the Trooper. You can see the difference right off. The Trooper has a 70Amp while the Rodeo has a 60Amp. This is what I am told.

altinstalled-hi.jpg


Removal is a pain, I want to thank a friend of mine for letting me use his store to do this. Nothing like having the truck on a Hydraulic lift for this.

After you remove the Alternator, I had to remove the bracket that held it as well. There is some kind of guard on the bracket that prevents the new alt from fitting in. I cut this guard off as you see in the first picture. I also needed a bit more room to tilt the bracket up fro the new Alt. You can see the sleeve on the top of the bracket, where I cut a groove down it. The groove allows the bolt to shift just a tad in the bracket so I can get both mounting bolts in. I don't think this is necessary, I might have been able to shift the bracket hard enough to do this without cutting. But this was easier.

mount1-hi.jpg
 

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mount2-hi.jpg

mount3-hi.jpg


This is a pick of the same Alternator in Doug Brown's Rodeo. I couldn't get a clear shot of mine due to failing light. But you will see the top bolt of the Alternator mount. This mount hits the exterior fan of the new Alternator. This must be ground down 1/8 of an inch. Grinding it flat is the best bet, since its aluminum it takes no time at all.

altinstalled2-hi.jpg


Now the bracket is ready to go back in and the new alternator attached. The new top mount is slimmer than the old alternator so I needed to put a about a quarter inch spacer in. These are the pictures from my Trooper (sorry the light it bad).

altinstalled3-hi.jpg

altinstalled4-hi.jpg


Remember I had to space the Alternator pulley out so it was level with the drive pulley. The new Alternator fits in, just a little tight. Here's where things get complicated.

First off, you need a new belt. The old belt is too small, there is not much adjustment room with the new Alternator either. I went with a 14mm X 1000mm, I think this is slightly too big, so I will try and find one between 900 and 1000mm later, as it is now it works, but I do get some squeak from it and it is as tight as I can get it.

Now we come to the wiring, If you have time to heat shrink some of the wires it will look better, I used Electrical tape and zip ties as it was getting late. I could get get any clean pictures because of the dark as well but this part is pretty easy.

There are 3 wires on a harness that connect to the pig tail of the old Alternator. Clip off the Harness pigtail and strip these wires, they will be connected to the new pigtail for the GM Alternator. You have 2 Keyed on wires and 1 Hot always wire, you can use a lamp tester to verify which are which. The two Keyed wires get attached to the yellow Pigtail wire while the Hot always goes to the red wire for the alternator. Shrink wrap/Wire nut/Electrical tape these together good and secure and plug in the new Harness.

The old hot wire coming out of the Alt to feed the battery is 2 8gauge white wires spliced into a ring connector. You can cut these off, or tape it up real secure and zip time them back out of the way. These wires will not be reconnected. Instead you will take a new 4gauge wire and crimp a ring connection to it, attach it to the back of the power of the Alternator then feed it up to the battery.
 

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wiring1-hi.jpg

wiring2-hi.jpg


Connect the new 4 gauge feed from the Alternator to the battery, I needed to buy a new battery terminal large enough to accept to 4 gauge wires and the 8 gauge feed at fuse box.

Old picture of terminal and new pictures.

Old:
wiring3-hi.jpg


New:
wiring4-hi.jpg


Lastly this is the old Alternator harness. The 3 small wires from the battery feed into this terminal, as well as the 2 large charge wires. You can disconnect the harness since it serves no purpose now. Not sure if leaving it in will effect anything as there is no longer power traveling through these lines.
wiring5-hi.jpg
 

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Nice work. Sounds like a good upgrade for anyone running a winch. During the last trip to GWNF Andy ran his winch so much pulling rigs out of the snow that his Trooper starting shutting down due to low voltage.
 

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Hi guys, so I've been scouring around looking for options to upgrade the alternator on my 3.2 and I've been coming up empty until now! I want to do this upgrade but the link you posted for the alternator is dead. I was wondering if you could give me some info on the GM alternator so I know what to buy?
 

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Discussion Starter · #10 ·
Another write up on this? swap on another forum listed "Part# is 20-146-10 180A/S4/3SHM" as the alternator used.
 

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Hello, I just joined this forum. I have a 97 acura slx with some electrical issues. I was wondering if yall thought a bigger alternator would fix this? I just had it tested and both battery and alt came back good but I saw someone had posted the same and replaced the alt and it fixed their electrical problems...

Problems I am having:
My volt needle moved a little when using the signal lights

AC blower fan works and then sometimes doesnt work (when it works, it works on all speeds but every once in a while it stops and I have to move from outside air to recircled air for the fan to work)

Sometimes the button will not unlock on the shifter to take it out of park (i end up having to put car key to ON and hold the button down as i start it)

Any help or advise would be greatly appreciated!- the alt looks stock and very dirty the car has 240k miles.

Thank you!
 
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