O/D on or off when driving down the highway

RVER wrote:
I have a adjunct to this question. I also have a fifthwheel and pull it with a Chevy 2500HD diesel with Alison transmission. I can not get it to say it is in tow haul or O/D off with using the button on the shift handle IF it is in D but if in 3 Both of them work. I am not sure they are not working in D but that it does not light up indicating that it is that mode of tow haul or O/D off which is the same button. IS THAT WEIRD or what? I have put it in tow haul while in 3 and then shifted to D and I think it works the tow haul. I like tow haul mostly for the way it uses the tranny for engine braking when pulling the fifthwheel.

Per the OWNERS MANUAL for 2003 Chevy 2500HD

Automatic transmission equipped vehicles are provided with a button at the end of the shift lever which when pressed enables tow/haul. When the button is pressed, a light on the instrument panel will illuminate to indicate that tow/haul has been selected. Tow/haul may be turned off by pressing the button again, at which time the indicator light on the instrument panel will turn off. The vehicle will automatically turn off tow/haul every time it is started.


If you have an automatic transmission, you can tow in DRIVE (D). You may want to shift the transmission to THIRD (3) or, if necessary, a lower gear selection if the transmission shifts too often (e.g., under heavy loads and/or hilly conditions).


So the little 'trailer icon' should come on when you select Tow/Haul
(1st push of button on end of shift lever)
O/D DISABLE if you push button again

Push it again and back to Drive O/D


Just give me the dang manual LINK

Oh, I thought it was for gearing down on hills. Rather than using the brakes for a long hill I turn overdrive off. If that doesn't slow me down sufficiently, I use the brake until I feel comfortable shifting down to the next lower gear to hold an appropriate speed going downhill.

I don't like to use the brakes on a long hill because they get hot and could catch on fire.

Consult your owner's manual.

I have a adjunct to this question. I also have a fifthwheel and pull it with a Chevy 2500HD diesel with Alison transmission. I can not get it to say it is in tow haul or O/D off with using the button on the shift handle IF it is in D but if in 3 Both of them work. I am not sure they are not working in D but that it does not light up indicating that it is that mode of tow haul or O/D off which is the same button. IS THAT WEIRD or what? I have put it in tow haul while in 3 and then shifted to D and I think it works the tow haul. I like tow haul mostly for the way it uses the tranny for engine braking when pulling the fifthwheel.

my car and truck I tow with does not have that OD thingie/selection on the shifter anymore.

matter of fact i think the top two gears in my F 250 are overdriven.

life is so much simpler now. :W

MEXICOWANDERER wrote:
If I may ask a question...

What does the designer and builder of the transmission say?

There is no discussion about this in the owner's manual?

You know real men don't read the instructions.

RVER wrote:
Thanks, did I do damage to drive with it off?

No of course not.

If you watch your tach, you will notice that OD increases the gearing just slightly and your engine runs 200-300 RPM faster without it.

OD is intended to help with gas mileage, mostly. YOu could run with it OFF all the time if you choose. In some unusual circumstances your gas mileage can actually be better with it off all the time.

Older cars, trucks and RV's didn't have Overdrive. There are still many of them on the road every day.

If I may ask a question...

What does the designer and builder of the transmission say?

There is no discussion about this in the owner's manual?

D and go unless it starts hunting. My OD is 98% off when towing. First downshift and off it goes.