I have a 94 f150 with 160k I recently just replaced the alt. And battery about 5k ago. The problem is whenever I put it in any gear other than park (while idleing, if im on the gas its fine) the batt meter will drop from about 14 to about 8 and will stay there, no accsesories,blowers or lights have an affect to it it will be fine in park with everything on or not.... Soon as its in gear it drops significatly ... Lights dim blower slows... Need help where to look.. Feeling its a ground or some sort of wire problem! .... It has the e40d trans... Thank you

 

Is the belt tight?

 

Short to ground if I were to guess, something going to the trans but I could be wrong. Bust out the DVOM

 

I recently removed the smog pump due to it seazing up... I had to find a smaller belt but the problem was there before also... And how would I find how much is supposed to drop at the trans wires when its running good?

 

put it up on jack stands

 

Sounds like a ground problem related to the neutral safety switch. You're gonna need a wiring diagtram and test light or meter. good luck.