I was heading to Fla and when going thru Tenn Up the I-24 hill to MountEagle. When We started down the other side, a 6% grade I put the unit on the Tow Haul mode to see what the grade breaking was like. Got down the hill a ways a tapped on the brakes and the Trans down shifted and started to slow down. All is well. Start going to slow so step on the gas pedal and engine keeps racing and will not shift back up. Tried taking out of Tow Haul and still stuck in whatever gear it is in and truck is running in red line area. Pull over on the big hill not a very good idea but had to do it. Pulled over and put unit in park. Put back in drive and finished trip to Fla with no other problems. Was this a fluke or did I do something wrong

Mark T

Nope, everything seems OK. Thats the way T/H is supposed to work. The dashed red line on the tach is OK to be in if its grade-braking that got you there. Obviously dont be pressing the accelerator in that dashed red-zone, but if the tranny downshifts and you are not touching the gas and it goes into that dashed red zone, it will be fine. However, dont let it get into the SOLID red zone. Avoid that area at all costs. What you describe as the trans being stuck in a certain gear is just kinda the way it works/feels when the Torque converter clutch is locked up in lower gears. Normally when you drive, the TCC doesnt lock up until 4th or 5th gear, but in T/H it locks up in 2nd and stays locked until you decelerate to about 15 MPH. Thats why it feels like the tranny is hanging its shifts or feels "stuck" in one gear. Sometimes if the tranny doesnt think it is appropriate due to the current conditions, it may take its time unlocking the TCC, even when you turn off T/H mode. If you turn off T/H mode and the TCC still feels like its locked up, accelerate a little, then let off. It should unlock. Otherwise, everything you describe sounds normal. Hope that helps!
---Ben

Thank You, I thought if you accelerated it was supposed to shift back up, but it must have thought it was not time yet. I will try it on the way back home.

I don't know how many times you've used your T/H, but the 1st couple of times I tried mine it did exactly as you said -- seemed not to realize I was giving it throttle after taking it out of T/H and (me) wanting it to upshift. Now I'm thinking it was in some sort of "learn" mode, 'cause mine doesn't take long anymore to realize it's out of T/H and perform an upshift. Would be interested to know if you've used yours much, and if not, if it improves after a few more tries?

Good luck...

ahhh yes...good point dan diesel. T/H and normal are two totally different modes on the Allison and therefore each has its own adaptive learning curve. Thats why if you add a chip/programmer and let the Ally learn, and then put it in T/H mode, it acts wierd because it has to learn again in T/H mode.

--Ben

maybe get on the fuel harder, if u are giving it fuel it doesn't want to be in the dashed red zone.

If u stab the brakes and let off in stead of constant pressure it won't downshift either.

Get on some smaller hills and try it, u won't hurt anything.

When it gets close to the solid redline it will shift to higher gear.

I use the tow haul on small hills at home, nothing like this hill. I do have to say I do not use the tow button very often maybe once a week and never towing anything heavy yet. Most of my towing will come in the fall when goose hunting starts. Thank you for all the input. Once again the PLACE is it for all the answers.