So I am new to the FMTV world and recently took delivery of a 2000 m1088a1 fro GovPlanet. That is a whole story in itself but I now have the truck and I am trying to diagnose what I think is an electrical issue. The truck is very low on power and only gets up to about 15mph on flat ground. Just doesnt get the RPMs up enough to shift. On a downhill it can get going and shift. Uphill I have to manually select gear 1 and barely move. I used a cheap code reader that tells me that there is high voltage. I have checked each battery and get about 12.3v and 24.5 or so when linked. I have replaced and checked the alternator and regulator. I have checked everything with a volt meter. What I do notice is that even though the batteries are topped off the alternator outputs 28v. I am thinking somehow it senses the batteries need a charge. I am thinking the problem lies with the "reverse polarity protection box". Not sure how that works though. I am guessing my other two options would be checking the ECM (requires a CAT mechanic) and replacing the really board in the cab (expensive). Does anyone have any experience with an issue like this? Or ways to trouble shoot?