I am new to this diesel thing...please bear with me. I just bought a '06 Chevy, 4x4, crewcab, LBZ. Bone stock with 15k miles. First diesel.
Traded off a '04 6.0 gasser. This duramax with the 6-speed Allison is AWSOME! Now for the question: How does the "Tow/Haul" work? I know you use it when pulling a heavy load...do you keep it on when you reach highway speed? What does it really do? I am sure I will have more questions, I don't know diddly about diesel's. I would also welcome any tips anyone would like to offer. I have learned a lot just reading the post here.

To quote Ron Popiel - "set it and forget it".

My 5er weighs in aroung 10k lbs (maybe a little more) and I love tow/haul mode. I just came back from Branson Saturday and pulled the hills between there and Ozark @ 57mph minimum. The grade breaking is unbelievable - going down one hill I touched the brake and the Ally shifted down twice and held me @ 70 mph. The wife kinda freaked when the engine shot up to 3800 rpms but that's what it's designed to do.

-chris

There isn't any reason for not using tow mode when towing. chevman

Put the ally in tow haul when your pulling something leave it on and forget about it. It changes yoru shift points, helps w/grade brakeing and prevents "hunting" shifting constantly.

a little info on tow/haul and its operation...


Tow/Haul Mode
Tow/Haul mode significantly changes the transmission shift pattern to reduce shift cycling and to deliver better performance, control, and cooling when towing or hauling heavy loads. For instance:

• Upshift points are raised at light to mid throttle position to use more of the available engine power for acceleration. Downshift points are raised to enhance engine braking to help slow the vehicle.

• During deceleration, the torque converter clutch (TCC) remains applied at closed throttle at lower speeds to significantly improve the effect of engine braking.

• During acceleration, the TCC is applied in 2nd range and remains applied in 3rd, 4th, 5th and 6th. This improves the drivetrain efficiency and significantly lowers transmission sump temperature when towing heavy loads. In Normal mode, the TCC generally applies only in higher ranges and is dependent on throttle position.

• Tow/haul is designed to be most effective when the vehicle and trailer combined weight is at least 75 percent of the gross combined weight rating (GCWR) of the vehicle.

• Operation of tow/haul in a lightly loaded or non-loaded vehicle will not cause damage. However, there is no benefit to the selection of tow/haul when the vehicle is unloaded. This situation will cause a firm shift. The tow/haul switch is not a performance switch.

• Selection of tow/haul when unloaded may result in unpleasant engine and transmission driving characteristics and reduced fuel economy. Tow/haul is recommended only when pulling a heavy trailer or a large or heavy load.

Activation
• Tow/Haul is selected or de-selected via a switch on the end of the transmission shift lever. A lamp on the instrument panel will illuminate to indicate that tow/haul has been selected.

• Tow/Haul must be selected again, every time the vehicle is started, if desired.