Allison 5sp: no forward gears lots of codes

[zvolena04]

tranny just quit no forward gears and set off 4 codes 721 722 727 735 is tranny bad

 

[Kat]

What year truck and any mods?

 

[zvolena04]

2005 and no mods all stock fresh transfer case new output speed sensor on transfer and input speedsensor on tranny, it went into limp about 20 miles before pulled over to reset ran could untill pulling out of truck stop it just cluncked and will not move forward but backes up fine

 

[Mike L.]

Speed sensor ( output, maybe turbine ) or transfer case.

 

[zvolena04]

if thoughs do not fix it are the odds tranny bad

 

[Bonestock]

NSBU Switch? I had one go on my 02' awhile back. Seems like I had a forward gear though?

 

[Mike L.]

if thoughs do not fix it are the odds tranny bad

No.