'97 Blazer with a new battery and a bench tested alternator (it passed) but when you press the accelerator the volts (dash gauge) drop from 14v to as low as 9v. Any ideas what could be wrong?

 

I have a 1998 that is doing the same thing, the voltage drops when the gas is pressed, and then when idling at a stop light, it replenishes.

 

Just went through this on my 99. Found the wires from the battery to the fuse box and to the alternator were just dust. I was shocked (bada boom) in the condition of these wires. This fixed a few problems I had.

 

it turns out to be the alt afterall!

 

im having the same problem right now. i put a new tensioner assembly on it thinking the belt was just slipping and nope... still does it. dont want to just throw an alternator at it next and have it not fix it though. its hard to see the alternator being the issue as it charges perfectly fine driving down the road, only dropping when it downshifts and goes above 3000 rpm, dropping it to around 9 or 10 volts. as soon as it shifts and the rpms drop, it comes right back up to just a hair over 14.

 

help please!!