Isuzu NPR alternator vacuum ports (2 Viewers)

[RufusTheDufus]

I'm planning to switch from the stock Toyota alternator in my HJ45 to the Hitachi unit used in Izusu NPR trucks. The Toyota is a 35 amp or 40 amp externally regulated unit. The Hitachi is a 70 amp internally regulated type. I've got the wiring changes figured out. I'm trying to figure out the vacuum pump connections.

Here's my guess at the way they should be hooked up. Toyota on left and Hitachi on right. Is this correct?

 

[doug720]

You are correct on the ports. I just connected mine a few days ago on my swap.

I did notice a good thing on mine. Going from the 2F with engine vac to the pump with the diesel, my brakes have a little more power assist now.

Doug

 

[RufusTheDufus]

Thanks for confirming. I didn't want to hook something up backwards.

 

[kennyhammond]

sorry to impose on your thread but i have a customers truck and it is a scout2 and the alternator/vacum pump went out (the #'s on the alternator are LT140-105b010) i can't find a replacement alternator to replace it with .... any suggestions.... i baught a lt170 and the lower bracket is to big for the alternator. PLEASE HELP.....

 

[RufusTheDufus]

I found mine through alternatorparts.com. The Hitachi page is at: National Quick Start Sales, High output alternator, Alternator & Starter Parts - Hitachi

 

[RufusTheDufus]

i baught a lt170 and the lower bracket is to big for the alternator. PLEASE HELP.....

BTW, I'll have to modify my stock lower mounting bracket to make the Hitachi alternator fit. I don't mind. These alternators are used in lots of vehicles and you can find them for $120 brand new at many parts stores.

 

[Creeker]

BTW, I'll have to modify my stock lower mounting bracket to make the Hitachi alternator fit. I don't mind. These alternators are used in lots of vehicles and you can find them for $120 brand new at many parts stores.

I thought I'd add onto this thread rather than starting a new one. I'm doing the alternator mod with the Isuzu NPR alternator. As has been pointed out, a bracket mod is needed. Here's what I'm planning, tho I feel wrong about cutting up the original bracket, it will be cheaper/more accurate than fabbing a whole new bracket. Please comment.

 

[fjbj40]

To save me some time would you please post up how you went about the wiring change? I have put a BJ60 internally regulated alt. on my BJ40 which was externally regulated but have not got around to wiring it up yet (truck is still being assembled).

Thanks,
Daryl

 

[jmattj]

NPR wiring

I too am trying to stick one of these in a Scout. Any wiring diagrams out there?

 

[jmattj]

Found it.
https://forum.ih8mud.com/diesel-tech-24-volts-systems/128585-isuzu-4bd1t-swap-8.html

 

[Dougal]

Some fantastic tech drawing there.
Someone found a higher amp alternator that fit the Isuzu with a vac pump on the back. But where and what?

 

[OilHammer]

What did you do for the pulley on that? I'm ok with the adapter bracket to mount the NPR, and with the wiring, but the pulley is a complete mismatch from the Toyota. Toyota is a large V belt, and the Isuzu is a dual tiny V belt....and the shaft is smaller than the Toyota shaft, so just swapping the pulley over is a bit more complicated. Maybe an adapter shim?

 

[RufusTheDufus]

I purchased a different pulley that matched the Toyota belt. I don't recall which one at the moment but if you have dimensions they most likely have something on this page that will work.

 

[FJSeattle]

good info here, exactly what I was looking for to hookup my isuzu alternator.

 

[mike]

I'm planning to switch from the stock Toyota alternator in my HJ45 to the Hitachi unit used in Izusu NPR trucks. The Toyota is a 35 amp or 40 amp externally regulated unit. The Hitachi is a 70 amp internally regulated type. I've got the wiring changes figured out. I'm trying to figure out the vacuum pump connections.

Here's my guess at the way they should be hooked up. Toyota on left and Hitachi on right. Is this correct?

What did you with the internal regulator? Did you remove it and connect the existing internal regulator wires together?

 

[Creeker]

To add to the general knowledge base, I bought my alternator from Amazon seller "Crank -n- Charge" in 2011.

New Alternator for Isuzu Medium and Heavy Duty Truck NPR Model GM 5…
Merchant SKU: 12234NPS
ASIN: B004N6VY48
Total: $159.95
12V, 80A, Neg Ground, Vacuum
​

I can't find a picture right now, and my truck isn't where I am...

 

[Creeker]

The 12HT bracket won't fit the the Isuzu Alternator.

You could fab one from scratch (I think that's what Tapage did) or you can mod the existing. The existing is incredibly beefy, and so far it has held up to my mod. I cut off one edge and welded in a new gusset plate.

You need to trim off the back unless you want to do something to extend the pulley shaft.

 

[Creeker]

I used the original pulley and fabricated a thin shim so that it would fit on the Isuzu shaft. Took a while snipping and sanding but it works.

 

[Creeker]

One more thing: I didn't do the bracket exactly like these drawings that I had done (above and below). Instead, we made the gusset thick enough and drilled a hole to align with the bolt. Again, sorry I don't have pics of the final. So where it says "solid stock fit and welded into bracket" nah, we didn't do that.

 

[Creeker]

For wiring, I got this from another thread; I'm afraid that I can't give credit, as I didn't write down the source! Anyway,

The alternator connections are very simple. The standard Isuzu alternator has an integral regulator which makes it even easier to wire up. Check Fig. 9 on page 6D-14 of the FSM for detailed wiring.

Basically, you have three wires going to a round connector on the back of the alternator plus a heavy black wire (B) going to the output stud also on the back of the alternator. This black wire should be heavy enough to handle the full alternator output (70 A) and goes directly to the (+) of the battery (might be a good idea to protect it with a fusible link or big fuse). The black wire (S) from the round connector also goes directly to the (+) of the battery. It serves to sense the actual voltage at the battery which the regulator uses to control the output voltage of the alternator. The white wire (IG) from the round connector goes to the ignition switch and should be hot only when the ignition switch is in the "run" position. This wire turns the charging system on and off. The white with blue stripe (L) is used to control the "Charge" indicator light and is optional. When the alternator is charging, the (L) wire is hot and turns on the "charge indicator relay". Since the indicator light is wired through the normally closed set of contacts on the relay, when the relay is turned on, the indicator light goes out. Hope that makes sense.

​

I ordered the connector from "The Repair Connector Store" Fresno, CA. Code/SKU RC20301 "Hitachi Alternator 3 and 4 Female Terminal Repair Connector".