tow mode downshifts

[buud]

while towing my 5th wheel (14,000 lbs) downhill in tow-haul the downshifts overrev the motor. 02' 3500 dully 6.6 auto. so i shift out of tow mode most of the time. can the shift points be reset? buud

[redrider#1]

To my knowledge, shift points on the Allison cannot be adjusted, but the computer will not allow downshifts on T/H to overrev the engine. It will allow the rpm's to get into the "red" area of the tach, but GM updated this "red" area at some point to a hashed red line whigh means the engine will not rev past this point under acceleration, but it is ok if the computer pushes into it due to downshifts up to a max of about 4500rpm(I thinks that is the real redline). My 2004 has the hashed red line, but I am not sure what year GM changed the line.

[DmaxMaverick]

The computer(s) won't let the engine rev above the compression redline, which is 4500 RPM's. On your tach, there should be a shaded red area, before the solid red. The shaded red area is intended for compression braking. If it reaches the solid red, it will upshift on its own.

Nothing to worry about. I've been "in the red" hundreds of times.

[Stlheadake]

Nothing to worry about. I've been "in the red" hundreds of times.

Tell me about it, I just bought an 06, believe me I know about RED!

I have the 6spd and it seems to shift fine even with 14K behind it. Nothing too dramatic, and just when it needs to. I don't know how it knows, but I love that tranny!