JDMC5

iTrader: (3)

06 TBSS. Has a built trans and a yank 3000. Shifts fine at part throttle but will not shift 1-2 at WOT. I set the rpm and mph ridiculously low but still no luck. The scanner shows the shift is commanding, its just not happening. I'm using hptuners.

Also, after a rewrite entire/ letting the vehicle cool down, it seems the first time we try for a 1-2 it will actually happen. But after that it's no luck.

EDIT:

The only thing I can think is that the TCM is bad or maybe wiring. That or the trans itself???

I tried a heavy throttle (maybe 50% throttle) 1st gear pull, ya know, to maybe give it a little extra time to figure itself out......lol, and still wouldn't shift.


has anybody ran into a similar issue?

JDMC5

iTrader: (3)

this is old but for search purposes it ended up being the trans.

mrvedit

Do you know what it was in the trans that was bad?
Also, when it didn't shift, did it seem to stay in 1st gear or did it seem to shift into neutral?

There are one or two other threads where the OP is reported no 1-2 shift and neither I nor anyone else has given them good suggestions yet.

JDMC5

iTrader: (3)

Felt like it wasn't shifting out of 1st, banging the rev limiter. Funny thing is it would shift fine every time until it got up to operating temp.