'92 with no charge from the alternator
 

Hey guys,
Been working on this problem for about a week now. Read all the stuff on the forums of things to try. Started with the easiest and cheapest, the voltage regulator. No dice, still won't charge the batteries. Then changed the crank position sensor. Still no dice. Changed the alternator, still no dice. So now I'm stumped, only other thing I can think of is the brain box is messed up somehow. Any ideas? Or some things I can do to test and assure myself those things are good. I put in all "new" parts, no reman junk. Thanks for any help you guys can provide.

I dunno how far this goes back if its on yer truck or not but my 01 has a battery temp sensor under the drivers side battery, if the battery is hot it wont charge no way:humm:

Thanks for the idea, but mine doesn't have anything like that, and the batteries are cold as can be with the cold front we've got here lately. Keep the good ideas coming friends.

got yourself some wiring schematics? in order for an alternator to produce voltage it has to have voltage supplied to the windings to start with... the regulator adjusts the strength of the charge by the ammount of voltage being put to the windings. usually if its just a regulator problem the external regulator will solve the problem. however junk parts do come in brand new boxes if you get what i mean. simple way to find out if the fields are being excited... hold a wrench to the backside of the alternator; it sucks to it... its fielded. in this isntance i'd look into the output from the alternator to the battery; and even excessive AC volt leakage. in order for a battery to charge direct current has to be applied. that will indicate the rectifier bridge (diode trio) is in tact just in poor condition. also if the rectifier bridge is damaged i dont think it'll stop charging but just charge very poorly

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also pull on your fusible links, if you find one that is "spongy" and stretches i'd be looking for a wiring problem somewhere; get ahold of some wiring schematics and identify what circuit it feeds. fix the short and replace the fusible link... i've also heard the small 3 prong box that plugs into the back side of the dash cluster can cause a no charge situation. they're like 20 bucks a pop too...

Thanks for the ideas, guess I'll be out there with the VOM meter again tomorrow. As for the dash thing, I'll have to pull it apart again, had it apart while installing the gauges on the dash, but didn't notice anything there. I have some basic diagrams for it, but it just shows some of the sensors going to certain pins on the engine control system. Is there any special adjustment to the crank sensor that would cause that condition, such that even though I replaced it, it's still not working properly? Thanks again for the help guys. Seems there are some quirks to how this system works, lots different than a GM 1 wire alternator.

the little 3 prong bugger is on the lower side of the dash around where your PRND21 indicator is

Ok, thanks again.

Bypassing the voltage regulator and shorting the field to ground, the system charges. Now to figure out why it's not telling the alternator to charge with the regulator and PCM system connected in. Is there a fuse or anything I should be checking?

Check for codes??

How on earth do you do that with it? :) Sorry, never had to do it on this truck, I can do it no problem on my Chevy. I'm assuming there is a test port or jumper of some sort? Thanks again for all the help guys, I'm just really frustrated at this point after putting this much money towards it and replacing parts that are likely still good.