Could it be a Short or a Pressure Switch?

have you tried any Isuzu forums?

for the record I highly doubt you have a short....that's the type of thing that blows fuses or causes something to energize at the wrong time.

Most likely it is a bad earth connection somewhere.

I'll drink to that. Check the connection between the engine & chassis - remove wire, check it, clean the ground contact ares. If that doesn't fix it, carry on looking for other grounds, clean & check.

If you are familiar to automotive electrical schematics, here's one for you, looks like you have a loose conection or false contact on a common wire, you'll need some splicing tape and a $10.00 digital multimeter.

Go directly to Fig. Fig.38 enlarge it and print it.

Good luck

Didn't we just cover this topic a few weeks ago?

Yes we did sir but I still am un able to find my problem.

It sounds to me like a bad earth connection, or simply a bad connection or even that your alternator brushes are worn out.

Buy the $10 meter that someone else recommended and initially check battery voltage with no engine running, then start the engine and watch the battery voltage for several minutes. Switch on the lights (I think you said) and note what happens to the battery voltage.

Note all the details and write them down here.....

Bad connections in the main battery circuit can get very hot quite quickly, watch your fingers....

A good alternator, once it has replaced the motor start charge should peak battery voltage at around 14.2 - 14.4 volts. More or less is generally wrong, though +/-0.5 volts error you can probably ignore.

Best of luck.

Agreed, from the symptoms I'd definitely recommend making sure the alternator is OK first.

Thank you all for your input. I did everything that was suggested and come to find out it was the alternator. Got the truck running and took the + post off the battery and it died, started it back up after giving it a full charge and checked the alternator and it is dead. Goes to show, Start from basics. Thanks again.

Just to reinforce it for others here, "Buy a cheap multimeter" and "learn how to use it properly".

The alternator was the most suspect part from the description.....but without some simple test equipment........

By the way, some alternators you can replace worn brushes, often this is the only problem when the output is gone or erratic.

Its certainly worth looking at just to gain extra knowledge.