MGM Problem
 

Ok,i keep having this same problem with my mgm and i must say it is getting really really OLD. after a couple of quick passes down the street, the motor starts locking up and then going into reverse. it doesnt matter if i am running highend matched race packs or an unmatched pack. still the same problem. i have checked everything and nother is touching that would short anything out. any ideas on what is happening??? at this rate, would i be better off to sell my system on ebay and buy something better?

Although I haven't a clue what the problem is, I can say I have two MGM 12012 controllers and haven't experienced that problem. You may have already covered these bases, but here are a couple things to check out.
Radio - have you made any settings changes since everything worked normally? If so, try changing those settings back to the way they were.
Does your radio have model memory? If so, try switching to a blank model (one you haven't programmed yet) and see if the default radio settings help.

Battery - as soon as the vehicle experiences the problem immediately switch the battery...does the problem stay with the new battery? If so, you can be sure it's not the battery. If the problem does NOT stay with the new battery, you may yet have trouble with your pack(s). Try putting them through a few cycles on your charger. Even just one cycle at low amps (1 or 2) can make a noticeable difference in packs that have sat for a few weeks.

Temperature - do you monitor the temperature? I did have a temp problem with braking on my 9918. At 120F, the brakes stopped working; every time. I know this isn't the problem you're having, but it's still something you can check. If you can monitor the temps, watch them at the end of each speed run and see if the problem occurs at the same temperature every time.

Receiver - do you have another receiver you could swap? This is highly unlikely to be the problem, but swapping is an easy way to rule out another component.

Good luck with it.

Try reprogramming the nuetral position, this happened to mine. After I reprogrammed it making sure the trims were all set at zero, it took some adjustment on the radio after, but all is well now.

re-mix...
do you have the mgm80? if so, is it alright to send you a pm about programming? i have asked this several times here, but keep getting a confusing answer..