i have a ppe on my lb7 duramax and every once and a wile i will be driving and it will down shift and i will lose my top gear. and say range shift inhebatied i will pull over and clear the codes and its fine. does anyone have any ideas?

 

I belive your limping your transmission...Congrats your in the "club" as the Duramax guys would say

 

Could also be NSBU switch. When does this happen, under hard acceleration? What codes are you getting?

 

most of the time its under hard accleration i P0700 or P0701 i beleave so may not be. but i dont think its limp mode because it will still haul *** just not have my top gear

 

It probably is still a limp mode then. There are different stages of limp modes depending on how severe the request is. If you can read the codes the trans is throwing to get the p0700. p0700 is just a MIL illumination request.

 

what do i do to fix it?

 

Your best bet is to back the tuner down and save for a Suncoast III or IV.

 

it only does it when im pulling my trailer. and whats the diffrence between them ?