You are not going to cause any catastrophic damage by running the "wrong way." The drive will become far too uncomfortable/distracting for you to tolerate LOOOOOONG before you do any damage.
Try it different ways and see how it works out for you. If it's "wrong" you will feel it in the seat of your pants.
I suspect you will not notice much difference between tow/haul on and off.
I suspect you will prefer to maintain manual control most of the time because cruise wants to maintain an exact constant speed, and will floor the gas pedal and shift the truck into second if it needs to, to maintain speed.
After a while you may discover you prefer to run tow/haul on in certain situations, and off in others. Same goes for cruise control; you may simply turn it off when the hills get too steep.
2002 Chevy 3500 DRW 8.1L/Allison
2000 Palomino B1500
...and the reason why I need a DRW to haul a Palomino:
2004 United 7x14 tandem axle enclosed toy trailer
2011 PJ 8x20 7-ton deckover equipment trailer
I am not familiar with how the tow/haul mode works on the Chevy Gasser transmission. The Duramax-Allison tow/haul mode locks the torque convertor and keeps it in a lower gear a bit longer. This prevents torque convertor "slip" which generates a lot of heat. I have a display that shows trans temp through the OBD port. City driving with the T/C results in a very hot transmission if I don't use tow/haul. I am unsure how other makes (Ford/Dodge) tow/haul functions.
mkirsch wrote: You are not going to cause any catastrophic damage by running the "wrong way." The drive will become far too uncomfortable/distracting for you to tolerate LOOOOOONG before you do any damage.
Try it different ways and see how it works out for you. If it's "wrong" you will feel it in the seat of your pants.
I suspect you will not notice much difference between tow/haul on and off.
I suspect you will prefer to maintain manual control most of the time because cruise wants to maintain an exact constant speed, and will floor the gas pedal and shift the truck into second if it needs to, to maintain speed.
After a while you may discover you prefer to run tow/haul on in certain situations, and off in others. Same goes for cruise control; you may simply turn it off when the hills get too steep.
You brought up some legit points.
T/H may work different on a lot of rigs. On MY rig it changes the shift points, meaning you will remain in each gear longer and it shifts a bit harder/quicker. In addition it kicks in the exhaust brake.
Overall it works well especially in hilly areas, the trans does less up/down shifting. I find with heavy loads out on the flats like interstate there is little to be gained by using it.
In addition the torque of your engine is a key player in how it performs. How much torque and what the torque curve looks like (how flat and where its at in the rpm band).
I would use T/H and cruise and experiment with how it performs for you.
Don
17 Oaks Ranch, Texas
US Army (RET)
'11 F350 4x4, CC, LWB, DRW, Lariat
AF 1150, solar, satellite
Vietnam Combat Veteran
racedrvr wrote: I am not familiar with how the tow/haul mode works on the Chevy Gasser transmission. The Duramax-Allison tow/haul mode locks the torque convertor and keeps it in a lower gear a bit longer. This prevents torque convertor "slip" which generates a lot of heat. I have a display that shows trans temp through the OBD port. City driving with the T/C results in a very hot transmission if I don't use tow/haul. I am unsure how other makes (Ford/Dodge) tow/haul functions.
In our Chevy gasser it's the same....because it's also an Allison (w/ 8.1L)
I find tow/haul to be too aggressive for a 4k lb camper. If you use the brakes for several seconds downhill the tranny downshifts and won't upshift until you speed up with pretty high revs for a while. I usually just switch it off to get it to upshift sooner. Even with tow/haul off it does a fine job downshifting after braking to below a certain RPM for awhile. Tow/haul works best for steep uphill or for roads that repeatedly climb up and drop again to minimize shifting.
The tow haul mode is for heavy loads, i.e. a camper and it reduces wear and tear on the transmission and the brakes which seems like the smart thing to do. With the Chevy trucks when tow haul mode is engaged and cruise control a feature, grade control is also active and controls the speed and handles downshifts. It works very effectively and on my first trip with a 3300 lb. camper and descending down a 10% grade for 20 miles down a mountain road I never had to touch the brakes.
If the Chevy has the transmission in Range mode the grade control is not activated. In tow haul mode the trans does not shift into 6th gear so there is no benefit to putting it into Range mode and shifting manually. This is true for 2011-2012 GM/Chevy trucks and other truck models or model years are likely to operate differently.
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