Check Engine light came on and the alternator gauge is low
 

I got a 1992 Auto trans and my Check engine light came on and I noticed the Alternater gauge was way down. Had the guy at Auto zone test the charging system and they came up with regulator was bad/low. Then the guy said the reg was in the PCM. How well do there testers work?

Does this sound right? Or are there other things to check?

I was reading the speed sensor could be bad and not reading the Engine speed to tell the PCM to charge But everything else seems to work ok. Trans shift good.

Adjacent to the turbocharger's outlet pipe, that goes to the intercooler, you'll find a bundle of cables going from the passenger's fenderwell over to the alternator side of the engine. There's a perhaps 1/4" cable in that bundle that is the alternators output line on its way to the battery.

In that bundle as it leaves the alternator going to the fenderwell, there's a plug and recepticle that allows one to disconnect the cable so one can pull the entire engine (I guess). . .. . make sure that plug is in fact plugged in securely. :pca1:

You may have a bad ecm, go to the sticky (I would post it up for you but I'm on my blackberry) and in there they show how to find out what it was by the code. Its really simple to do.