Charge light is on, truck shuts down as soon as the battery's disconnected...something's gone bonk in the alternator. However, it's not the brushes (my first guess and hope). I can't find my multimeter so I can't positively say they conduct, but there's plenty of material and the springs work. What's the voltage regulator? Is it the "IC regulator" in the FSM diagram? How do I test it, and what else should I test before throwing in the towel and just getting a whole new alt?

This is a Bosch alternator on an 86 2WD 22R truck.

 

I would just get a new one. But if you want to take the time look it up in the manual.. What year is your truck? I'll give you the right link once you respond back.

Found them
https://www.yotatech.com/forums/f128...-years-156128/

 

86 (see above )

I already have the 85 one, but I don't understand what it means by "IC regulator".

 

you could take it to az, or advance and have them test it for ya for free

 

Taken, tested, failed on all three counts, got a brand new (supposedly not reman) one.

Took it home, installed, fired up, disconnected the battery and engine ground to a halt. It *is* supposed to run without the battery, correct?

Ground lead and plug in the back both connected, belt is reasonably tight.

Suggestions?

 

Unless your battery is run down enough not to support running the engine alone. Youve run the battery down pretty good it sounds like. Did the light go out? Its prolly ok give it time to charge back up

 

The battery indeed ran down, but it was replaced two days ago and the new one seems to have plenty of juice left - engine cranks at normal speed and fires up just fine, the lights work, aso. When I fired up the truck, the charge light stayed on, and when I disconnected the battery, the engine died.

I'm going to dig up my multimeter, or get a new one, but is there anything I should test first? Fusible link somewhere?

Thanks for your help!

 

Bump?

 

The regulator is built inside the alternator, "ic regulator" first question....

When you get your multimeter going.... static voltage across the terminals should be about 12.5vdc with the engine running, it should be about 13.8v give or take a few tenths... if that's the case, you're fine.

 

Across the battery terminals, or the alternator outputs (and if so, which of the three wires in the plug do I test through)? That's with everything connected?