Alternator Upgrade : Nippondenso 90/120/140/etc Amp

So your factory 35 Amp Mitsubishi Alternator sucks and can barely keep up with your headlights, heater and windshield wipers running at the same time? The Internal Voltage Regulator crapped out and now the truck isn't charging? You could buy a replacement alternator, exactly like your old one, but why?


Enter the Nippondenso Alternator, found on Dodge Caravans with the V6 engine and Dodge Trucks (1988 - 2001) with the 3.9, 318 and 360 TBI engines, Magnum V6 (3.9L) or Magnum V8 (5.2L / 5.9L). The lowest output Nippondenso puts out a whopping 90 Amps, many are 120 Amps, some are even higher (approaching 200 amps in some rare cases). The best part, all of them are the same external size and almost identical in size to the Mitsubishi Alternator found on D50 Trucks.


So, how do you go about fitting one of these monsters to a D50?


Step 1 : Find a Nippondenso Alternator (Find a Used One or Buy a New One)

Step 2 : Buy a Chrysler External Voltage Regulator and Pigtail (any chrysler product 1971-1987) For simplicity and guaranteed results on getting the right stuff, buy one for a 1973 Plymouth Duster. This regulator and pigtail are always in stock at every parts store. You'll have about $20 invested in the Regulator and Pigtail.

Step 3 : Swap the Pulley from your Mitsubishi Alternator to the Nippondenso Alternator (because most Nippondenso Alternators have a Serpentine Pulley, some Early 88-91 models have Dual V-Belt Pulleys though)

Step 4 : Loosen your Upper Alternator Bracket/Adjuster Bracket and rotate it up a little bit (about a 1/4" or so). The Nippondenso alternator upper mount ear is slightly taller than the mitsubishi alternator.

Step 5 : Wire up the Regulator Pigtail, connect the wiring to the alternator and add the Ground Strap from the Alternator to the Battery. The entire regulator harness only requires you to connect to 1 Wire from your original D50 Alternator Plug. The Blue Wire connects to the Blue Wire on the Regulator Pigtail (see attached photos).

Step 6 : Mount the Voltage Regulator. The best place is the Passenger Side Inner Fenderwell, about 6" in front of the firewall. There are already bolt holes (threaded) in the fender well in this location. It puts the regulator close to the alternator wiring, as well as the main wiring harness, should you choose an alternate Ign+ Feed

Step 7 : Reinstall your Belt.


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It doesn't matter which of the 2 small field posts on the alternator you connect the Green and Blue Wires to, the circuit works exactly the same on either posts, but you must have the green on one post and the blue on the other. The Blue wire is the Ign + (on both the D50 and on older Chryslers) which supplies a field to the alternator and + to the regulator, the Green is a pulsed output from the regulator.



Congratulations, you now have a monster alternator that bolts in place of the factory alternator, is readily available at any parts store or junkyard. You also now have an easily serviceable/replaceable and readily available external voltage regulator that can be swapped in under 2 minutes.

The Initial Installation takes about 25 minutes on average, requires no permanent modifications to the truck, and makes it easy to service the charging system with readily available parts.

I used to have a 1991 dogkota that the alternator signal from the computer quit working. My friend who owned an alternator shop tried to do this exact conversion on the dogkota, but it would not work right, so he used an external Ford regulator instead. I never had charging problems after that - the rest of the truck is another story.

Funny, Pennyman. My Dakota (now a Turbo Diesel...the old 5.2L Magnum V8 donated its alternator to my D50) had a problem with the computer too, and for some reason I had a problem getting the External Regulator Conversion to work on it too.

I fought with it for ages, until (just for laughs) I "borrowed" the regulator from my Plymouth Duster and the truck started charging... The brand new regulator I had bought was bad out of the box.


Technically speaking, the Nippondenso alternator functions exactly the same as the old (60's - 80's) Mopar 60 Amp, 78 Amp, 110 Amp and 200 Amp (Ambulance/HD) Alternators. The only difference (other than appearance) is that Mopar moved the Regulator into the Computer on the 88+ Dodges.... Bad Move, the Regulator in the Computer has been the Bane of Mopar Existence ever since.

You're right though, it doesn't "have" to be a Dodge External Regulator (though it is the easiest to find and is in stock everywhere). Pretty much any regulator that was in use in a Dual Field Application will do the trick.

It has something to do with the computer and the wiring, even though it was no longer connected to the alternator. I even gave him 2 or 3 working voltage regs like the one you used - no luck. In our trucks that should not be an issue - just threw it out there in case someone had a problem with the install.

would this modification work on a 1990 2.4l d50?

Absolutely - his directions are spot on!

well i had a alternator off of a 2000 dodge 2500 5.9 magnum,and not sure if it was a bad alternator or fucked up the wiring, does anyone have a really clear wiring diagram? as im not wiring inclined. and is there a certain alternator out of a specific make/model/year that works better since i have a 2nd gen?

I ended up pickin up a 120 amp alternator off a caravan, pigtail and regulator from a 87 dakota for $25.02. Trouble is the pulley on my stock Alternator did not fot the Denso alternator. Had to run back to the boneyard and found a dual pulley set up on an 89 5.9 dodge van. If doing so do not forget the spacer needed on the new pulley. Whole ordeal took 4 hrs but I'm happy finally getting the pieces together.I will be installing everything tomorrow.

I run an ac delco 10si in mine. It is internally regulated and can make use of the stock wiring, but you have to make a bracket to get it to bolt up to the front engine cover. I actually run a 10si in the ram50, have one in the 62 falcon thats not on the road any more, and will be running one in the 68 f250 when I get around to that project. All three have a group 24 battery in them too. Fleet interchangeability is convenient.
The 10/12si are produced brand new in really high outputs as well.
Not quite as cool as as adapting a dodge sourced alternator, but it's been trouble free.

That is what Geronimo has a well - ran it for 12+ years until it finally went. Had it rebuilt and back on the road again with better parts.

Dang, didnt know the AC Delco was an option. http://imgur.com/gallery/ETjzqSD

Pennyman, mine has been bulletproof too. The only time i thought it was acting up, I had a poor connection.
I'll have to pull mine out and do a write up with the bracket modifications.
http://www.madelectrical.com/electri...elcoremy.shtml has a lot of great info on these, and car wiring in general.

what motor ? I fab'd a bracket for a brand new 'small case' GM alternator (97 grand prix?) onto a 2.0 starion motor
alternator shop recommended/supplied it. He made up a simple little pigtail that plugged in.... all for a low price
swapped to a v-belt pulley

google -starquest gm alternator- you'd find many options/installs, for the 2.6
check if starquest accessory layout differ from truck tho
3000GT unit bolt straight on to starion 2.6(+pulley change); http://www.starquestclub.com/forum/i...6&#entry226615

Quick question. For the B+ terminal I dont have to run a separate wire to the battery do I? I ended up wiring everything the same except no stand alone wire from alternator to battery. Currently is not working charging. Maybe the boneyard regulator is caput. I did ensure to give a ground to the regulator.

Putting an alternator bon that's ablout 3x the size or bigger won't hirt any of the other electrical components or anything, will it? I've got a stereo system in my truck. But I can't even use it because it kills the battery.

Bigger is always better with batteries and alternators. You will find anything that has a higher current pull will work better (like full car audio systems running amplifiers, the starter motor or decent headlights and driving light combos). The system will only ever push it's peak voltage into the wiring harness and nothing more (13.8v-ish if it's being regulated properly) and the wiring is already gauged for it's respective application. It's when the system is under heavy load/current draw that things can go wrong (recently did an investigation into why my friends' Kia Cerato "potato" was blowing low beams - it pushes 14.45v through each individual light circuit, just bad design from day one...) Most Kias suffer from this issue...a voltage drop and better fuse system and the headlights would last a decade rather than a few months.

I'll just add (not that it has relevance on this board) that you don't want to apply that to permanent magnet alternators like you find in motorcycles. There are no rotor windings to control the output of the stator. They run "full throttle" and the extra watts are dissipated by the voltage rectifier/regulator. An excessively large alternator will reduce the life of the regulator/rectifier significantly. That's why motorcycle alternators are often sized very close to their intended load, and bikes with a bunch of accessories have regulator/rectifiers with huge heat sinks.

Do the Montero alternator have the same size shaft. If I get one of those. And just switch the pulley's?

Edit 9-28-20 See post #35 for a synopsis of what I did end edit

There are two pictures I have added of mine, one of all 3 wires and one of the T configured spade connector.

If I understand correct the white wire with blue dashes gets abandoned and I connect the pigtail off the regulator to a field post of the new alt. Then I connect the blue wire to the other field post and splice the pigtail off the regulator into it. I think that white wire is my ground but it may be + wire. Whichever it is do I need to run a wire directly to the battery to be either ground or pos?
http://www.mightyram50.net/vbulletin...id=25681&stc=1 http://www.mightyram50.net/vbulletin...id=25682&stc=1

I pulled the trigger on a new alt and the pigtail/ regulator.
I still find it hard to believe I have to abandon that wire but surely I should be able to figure out how to make it work.

Well another option is to install the alternator off a van/conquest with a 2.6. I found one online for $70 https://www.ebay.com/i/382657872596?...hoCqfUQAvD_BwE

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Originally Posted by Salteen

Well another option is to install the alternator off a van/conquest with a 2.6. I found one online for $70 https://www.ebay.com/i/382657872596?...hoCqfUQAvD_BwE

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I went with one for a Dakota. I'm debating whether or not I should put it on my dakota and used the used one on the ram50. it was $88 for all three parts delivered. It's a pure energy new alt, well if not new they don't ask for a core. I just looked at RA again and they've increased the price by $22 and it says there is only one left. ?!

If it works that well, pull the trigger. Just seems to me that on most trucks a 90 amp would be sufficient and easier to install

But then again you dont get the bragging rights. The 'unique' rights.

The Dakota I have is a 90 amp. You can get them up to 120 afaik.

I have the parts, haven't got to it yet. hoping to be able to in a few days.