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Topic
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Greetings Everyone,
I need a little help diagnosing a 1998 Isuzu Trooper.
Here are the symptoms.
When I first received the Trooper the battery was dead. Replaced with a brand new one. The new one was not being charged as indicated by the dash lights and volt gauge at 11 volts.
I removed the alternator and it tested bad. Took it to a local reputable re builder and had it rebuilt. Installed the rebuilt alternator and all of the dash lights are gone. I let the truck sit and idle in my shop for about an hour and had no issue assumed truck was fixed.
As soon as putting a load on the system it fails to charge. Head lights, and heater fans and radio kill the battery.
Removed the rebuilt alternator had it bench tested. It bench tested to 14.1 Volts and passed the bench test.
Volt meter shows only 12.6 coming from the alternator no more no less in essence when on the truck the alternator. Which explains why it will run the truck with no load but dies when headlights, fans and radio are run.
Cables are good and have been replaced. Only popped fuse I found was a radio fuse. There are no alternator charging relays on the truck that I can find (this truck does not have the mysterious blue charging relay).
I am now lost.
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If the voltage output is 12.6 then your alternator is not putting out.
The alternator still sounds bad.[quote=”SigSaurP228″ post=156362]Alternator puts out 14.1 on bench test.[/quote]
I’ve seen things test right on the bench and make you chase your tail.
The important thing is does it work in the vehicle. see if this link helps
with the wiring/ checkhttp://www.justanswer.com/car/7ophv-isuzu-trooper-isuzu-trooper-3-0-td-ago.html#re.v/457/
Testing it on the bench when it is not loaded down with all the accessories that vehicles have these days is not a valid test. Like college man stated the only thing that matters is how does it work on the vehicle. I don’t know what your financial situation is but best bet is to get a new alternator.
I agree with the above post. I also would add that a starter can work fine but have an internal short causing a huge power draw.
Might suggest you look at :
1 The charging relay that’s blue and sits in the engine bay fuse box .
This can often fail and give the signs of a duff alternator .
2 It appear there is something (fuse?) Its built in to the lead off the battery terminal on the alt and it goes to the starter or battery terminal on the vehicle.
Can’t really tell (lousy image)
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