1st Tow, No Overdrive????

[jstbks]

Just returned from a short 105 mile trip pulling a 5er and boat, total weight of 11.5K lbs.
I could not get the transmission to shift into over drive! I have the 8.1/A combo and the truck had plenty of power and towed in 4th great. Anyone have any ideas why it would not shift into OD? I took the boat to get gas when I got home and the OD worked ok.
I tried pulling at 55, 60 and 65 with no change.
Truck only has 850 miles on it.

Brian :confused:

[mark45678]

next time try turning OFF the tow haul at that speed. it likes to go in the 70's to hold OD..... GOOD IDEA GM???? I think not or try turning on the cruise and set it low like 35 and drive it with the gas peddle, for some reason GM changed the shift pattern with the Dmax maybe the 8.1 too?

[imported_]

In the toe haul mode mine won't go into fifth
until you go 65 to 68 mph.Problem is ohio
has a strict 55 speed limit.It's also dangerous
to run 65 with a load trying to get into high gear
on some of the roads around here.

[Jackmchome]

Brian, You probably do not have a problem. On the Duramax it will not shift into 5th, while in tow/haul, until about 62mph. At speeds lower than 62 it is not in it's effective torque range.

I do not know the perameters set up for the 8.1, but if you look at your tach when it finally does shift to 5th I think you will see it at the bottom end of it's torque curve.

As said above, you can force the shift by turning tow/haul off, letting the shift occur, and then turn it on again.

Happy towing!! Jack

[ 05-20-2002: Message edited by: Jackmchome ]</p>

[jstbks]

My thanks to all! I will try the tow without "tow/haul" this weekend.

Life is grand for us weekend warriors with lots of power!

[Onebigcanuck]

Tow in Tow Haul to around 55+ MPH. Take the truck out of Tow Haul and release the pedal, it should drop into O.D. Put back in Tow Haul and in time it will remember. At least the A/D does.

Try it.