What does tow/haul button do?

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
747
I know it holds shift points to a little higher rpm, but what does it do for passing, fuel economy, etc.?

I assume it just sucks more gas by keeping rpms up keeping the engine in a more responsive torque range.

Any benefit to driving with it on?

04 Dodge Ram 1500 with 5.7 Hemi 5-speed auto.
 

Jeepster04

Chief Petty Officer
Joined
Jan 5, 2009
Messages
481
Re: What does tow/haul button do?

Keeps it in a lower gear longer before upshifting and it keeps it out of 5th gear on the 45rfe trannys.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: What does tow/haul button do?

It also downshifts earlier and can seemingly contradictorily hold a gear in lockup under a hard pull before downshifting longer too. Should ultimately reduce "hunting" between gears as well.
 

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
747
Re: What does tow/haul button do?

So i should definitely have it off when cruising on flat freeways. I like the better fuel economy of 5th gear.

So would it be beneficial for short hauls through town with lots of stop and go, or should i just leave it off?

Hauling 18.5' glastron on steel trailer.
 

Huron Angler

Admiral
Joined
Apr 7, 2009
Messages
6,025
Re: What does tow/haul button do?

I believe it's the same as "overdrive off" on my Ford. It keeps the transmission from shifting excessively and is good when towing is what I've been told, as mentioned.
 

EMC 1810SS

Petty Officer 2nd Class
Joined
Aug 20, 2010
Messages
176
Re: What does tow/haul button do?

Not sure about the mopars, but the Chevys increase the line pressure to the clutches also.
 

msojjo

Petty Officer 2nd Class
Joined
Apr 28, 2010
Messages
176
Re: What does tow/haul button do?

It' is basically what was stated above. It is an electronic switch that allowes the tranny to shift at a higher rpm, or a shift point. It also keeps the tranny from "hunting gears" as this will heat up your tranny in a hurry even with a cooler, this puts alot of strain on the transmission. As far as going down the highway with it off, well that depends on the load, if your carrying a light boat or just about maxing out the trucks towing capacities. If your on the heavier side i would leave it on, and the computer will find the most comfortable gear, and it will eventually find the 5th, or top overdrive gear, if there isn't too much strain on the engine and tranny. That only applys to the tow/haul button, not the o/d off.
 

Silver Eagle

Master Chief Petty Officer
Joined
Mar 16, 2010
Messages
852
Re: What does tow/haul button do?

I know it holds shift points to a little higher rpm, but what does it do for passing, fuel economy, etc.?

I assume it just sucks more gas by keeping rpms up keeping the engine in a more responsive torque range.

Any benefit to driving with it on?

04 Dodge Ram 1500 with 5.7 Hemi 5-speed auto.

I have a Quad Cab with your set up. I use it all the time when towing. I pull a 24 ft pontoon boat with Tandem wheel. .It's a must use thing. Mostly it keeps the truck out of over drive so you don't tare up the transmission. I get around 13.5 towing with it on. I keep it around 55 to 60 most of the time except when passing.Some times I use it in the city with out towing anything and my mileage is better then when not using it.
 

bkwapisz

Chief Petty Officer
Joined
Oct 20, 2009
Messages
441
Re: What does tow/haul button do?

Not sure about the mopars, but the Chevys increase the line pressure to the clutches also.


That makes sense; when I leave mine on without a trailer it shifts as though it has a shift-kit installed. Really slams into second and third. Also holds the shift for longer periods. Not sure about the fuel economy but I only use it when I pull heavy stuff.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: What does tow/haul button do?

Not the same as Ford's overdrive off. That blocks overdrive, GM changes all shift parameters.
 

bigrockets

Seaman
Joined
Jul 12, 2010
Messages
63
Re: What does tow/haul button do?

GM's web site says you void the transmission warranty if you tow with it off.
 

Huron Angler

Admiral
Joined
Apr 7, 2009
Messages
6,025
Re: What does tow/haul button do?

Not the same as Ford's overdrive off. That blocks overdrive, GM changes all shift parameters.

I knew someone would let me know I was wrong on this post;)

I'm curious now, I must be in overdrive the majority of the time I'm towing because when I turn OD off, my RPM's immedietely drop or increase depending on the speed, and while towing it seems to keep the shifting to a minimum while going up or down hills.
 

'96 Charger

Petty Officer 1st Class
Joined
Sep 7, 2010
Messages
223
Re: What does tow/haul button do?

In my 09 Ram quad with the 4.7 and 5 speed tranny mine not only raises the shift rpm's but it also downshifts while going down hills to keep from having to ride the brakes. Also keeps the engine from straining in a gear it has no business being in while towing.

On a sidenote, how would GM know the tranny wasn't in tow/haul while towing?
 

Todd157k

Petty Officer 2nd Class
Joined
Jul 12, 2010
Messages
114
Re: What does tow/haul button do?

In my 09 Ram quad with the 4.7 and 5 speed tranny mine not only raises the shift rpm's but it also downshifts while going down hills to keep from having to ride the brakes. Also keeps the engine from straining in a gear it has no business being in while towing.

Exactly the same on the Hemi's.

also a little side note: If you ever want to over-ride the speed limiter on the Dodge Hemi p/u, hold the key in the start position (after the car is already running) and you'll here a "ding" in a few seconds. The speed limiter is then defeated.
 

'96 Charger

Petty Officer 1st Class
Joined
Sep 7, 2010
Messages
223
Re: What does tow/haul button do?

The gubbener has it at 105. That's plenty fast:eek:
 

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
747
Re: What does tow/haul button do?

Thanks for all the feedback...especially how to override the speed limiter:D
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: What does tow/haul button do?

I knew someone would let me know I was wrong on this post;)

I'm curious now, I must be in overdrive the majority of the time I'm towing because when I turn OD off, my RPM's immediately drop or increase depending on the speed, and while towing it seems to keep the shifting to a minimum while going up or down hills.
I could be wrong too, but I've had both recently. 2003 Ford Expedition and 2008 GMC 1500. For me the Ford button (OD Off) was just like shifting to 3 (from D) in the GMC. With the Tow/Haul button on, the GMC behaves differently from all speeds and pedal (throttle) positions.
 

avenger79

Lieutenant Commander
Joined
May 5, 2008
Messages
1,791
Re: What does tow/haul button do?

ford's od off is essentially exactly the same as GM tow/haul it's the whole you can't call it what we call it thing. the ford will change the shift point and "alter" your gear ratios to increase towing and lessen hunting gears.

you can pull in OD on a flat highway and retaing good fuel mileage. if you notice the tranny hunting for gears or going in and out of OD hit the switch. I've pulled a 26 foot camper with my 1/2 ton ford in OD and no probalem at all. I wouldn't do it through the mountains though.
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: What does tow/haul button do?

It not only changes the tranny but also the motors programing as well.

Not at all like OD switch in fact completely different.
 

paultjohnson

Lieutenant Commander
Joined
Jul 29, 2010
Messages
1,560
Re: What does tow/haul button do?

Exactly the same on the Hemi's.

also a little side note: If you ever want to over-ride the speed limiter on the Dodge Hemi p/u, hold the key in the start position (after the car is already running) and you'll here a "ding" in a few seconds. The speed limiter is then defeated.

Wouldnt you then grind the starter to death, as the starter gear tries to engage a allready spinning flywheel ?
 
Top