Npr Budget Truck

[nympfisher]

hi,
i need some help on the charging system on a 1993 npr 4 cyl disel.
i have replaced the alt and the charge relay, the L terminal on the alt from the charge relay has no power, the voltage should come from the alt as i see it from the wiring diagram, this turns on the charge relay and cuts off the charge and warning lights and supplies power to the a/c fuse,,
have talked to several isuzu experts and no one seems to know the answer

[rcope]

Originally Posted by nympfisher

hi,
i need some help on the charging system on a 1993 npr 4 cyl disel.
i have replaced the alt and the charge relay, the L terminal on the alt from the charge relay has no power, the voltage should come from the alt as i see it from the wiring diagram, this turns on the charge relay and cuts off the charge and warning lights and supplies power to the a/c fuse,,
have talked to several isuzu experts and no one seems to know the answer

Hi,
I have the same issue with my Isuzu NPR and don't seem to be making ground figuring it out. What did you determine was causing the problem on the NPR charging? My email is [email protected]

[nympfisher]

it actually turned out to be the alternator. we had it rebuilt and the shop said it was charging,, i took it back to them to retest and when they applird power to the field lead it did charge, according to their test it is the correct way to test it.
we couldnt find another problem in the truck , diagram showed no way for power to get to the alt, so we ordered a new alt from isuzu,....wahhhh,,,, same problem..lol,, we had to laugh because we didnt know what else to do.
after talkin to all the factory trained techs on the southeast coast , i still did not have a answer, they said they didnt know how the system worked,, kept saying it was charge relay, i said no way,, its a simple relay , nothing special about( i opened it ).
finally i found a man in the town where i live that works on diesels at his private garage , he said that he had same problem before and that he discover that in the diagram for the alternator itself there is a diode the lets the alt self exite and then sends power out the l terminal to turn on the charge relay, so i said it has to be the alternator then.. (a bad new alt ? it happens )
i called isuzu and told them what was going on and the parts man said well i have 2 more in stock, installed another and it worked great.
,, sorry for the long version but it really is alot to go through to find out we had 2 bad alternators and the all the so called experts dont know how their system works,,
good luck

[RC745]

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