Transmission

[Kerry Warren]

my father-in-law has a 2500 durmax with an allison tranny when he is towing especailly uphill the tranny will downshift like it suispposed to but will stay in the gear wont shift again after that and the check engine light will come on unless he pulls over shuts off the truck and has a smoke then starts the truck back up and everything is fine until of course he hauls uphill again anyone have any ideas?

 

[THEFERMANATOR]

Sounds like limp mode. Need to have it scanned with a GOOD scanner like EFILIVE or a TECH 2 to see what trans codes are in it(most generic OBD2 scanners will nOT read the ALLISON TCM and you will only get a P0700 code).

 

[Rifleman3]

Sounds like someone is going to need to build a tranny soon

 

[Kerry Warren]

yea he just replaced the tranny