my gen light will come on after about 10 mins of driving, ive changed the alternator already and the everything works still including the tach and voltage gauge it reads right at 12 volts,down from the normal 14 it usually displayed. the batterys still have a full charge. what could be the issue?

 

check your grounds make sure there clean and tight .also check the crank sensor and wires ,itr could also be the PCM

 

Where exactly is the PCM, and crank sensor?

 

Pcm is behind the turbo on the firewall, their is no crank sensor on 12v unless rebal is refering to the tach pickup. I had the charging circuit in the pcm on my dads 96 go out and had to get my alt converted to internal regulation. It now works flawlessly.

 

Thanks that helps a lot

 

That unit above the dampener is more than a tach sensor it has input to the PCM for the automatic transmission Also lets the computer know that the engine is running for other systems. If you put alt regulator on I think you mean external regulator. There are step by step instructions in this forum and others.

Floyd

 

The Crank sensor and related wiring is usually the culprit with these types of problems. Where the wires go across from the IP and head then turn down behind the fan, they can become chaffed. Also near the end of the harness near the firewall is a wear spot.

As was said, it is an important sensor affecting charge, AT shifting TC lock, cruise control and a couple other functions.