Alternator issues?

[DawgTSi]

First off, let me apologize if this is the incorrect forum. I didn't see a specific electrical forum to post this in.

 

I have a 1997 GMC Sonoma 4.3 4WD manual transmission with a Vortec supercharger, Crane Cams ignition, and a few other goodies.

 

Now, I was driving home tonight and suddenly the battery warning light came on. My volts had dropped to about 10-11 and when I accellerated, the truck bogged down. I realize that these are all signs of the alternator going out, but what struck me as odd, is that the TACH had stopped working as well. The truck would still idle fine (running off of battery power), and when idling, the tach would jump up to about 750rpm... but when I put a load on the engine, the tach would drop to zero and stay there.

 

Is this a common feature when an alternator goes out on a GMC?

 

Thanks in advance.

[GM-Tech]

When voltage drops low, don't expect anything that is electrical to act in a normal manner. Fix the primary problem first, then re-evaluate.