Just a quick question, I have a 28 foot car hauler, triple axel, 11ft tall, should I keep the tow button on at highway speeds, or is it safe to drive the truck in overdrive?

Thanxs

Your tow/haul button has 2 different functions if your truck is 03 or newer.

One quick touch puts it in tow/haul mode which locks up the torque converter above 2nd gear which reduces transmission temperature and allows for grade braking. It also shifts later holding the gears longer for more power and automatically shifts down through the gears when slowing down to aid in slowing down. It does not lock out overdrive.

The second function is the overdrive lockout. This is enabled by holding down the same button for a couple seconds. This will restrict the truck from shifting into overdrive.

It is safe to pull your trailer in Overdrive but I would enable tow/haul mode.

You will notice two different symbols on your intrument cluster that will help you distiguish between the two modes.

Agree with Max Power. Just leave it in Tow/Haul and pull away.

I've used the tow mode, but it seems like it never shifts into overdrive. I end up taking it out of tow mode to get into overdrive.

Jim

It will shift into overdrive at about 60mph with tow/haul on.

It will shift into overdrive at about 60mph with tow/haul on.

Same here, mine kicks in at around 65 Mph. Seems the tow mode is not necessary unless your towing over 5 tons or so.

For you guys that race alot, which function is the best, tow haul on, or overdrive off?

When I ran my truck I found that leaving the tow mode off and leaving the overdrive on gained me the best E.T.

My truck isnt quite broke in yet, so I havent ran it hard , but it seems like haveing the overdrive off would yield the best results...but maybe not.

It will shift into overdrive at about 60mph with tow/haul on.
with my little stock tires she shifts into 5 at exactly 52mph.

i have a little question-

if the allison locks up for 4 and 5, then what is the point in puting it into t/h once your up to speed? it's lock either way right?

nosliw, you won't have grade braking when not in tow/haul. See Max Power's explanation below, it is right on. JJ :)