Tow/Haul Mode

[asr524]

Originally Posted by ysidive

When I said GM... I was referring to the GMC truck the one who posted drives.... I am well aware that GM has many and has had many brands......

You forgot the C in GMC so it reads as if you didn't know what GM was

All good...it might help someone reading who doesn't know though.

[Dakota 1120]

Originally Posted by archiebald1

I always use tow/haul mode pulling my camper or boat. Saves transmission and brakes

Ditto ... and get better MPG too - at least on the Midwestern Prairies.

[D W]

Originally Posted by trailerdude

I've used one of these when we had a Civic that would drain the battery overnight. It worked slick and didn't have to worry about the car starting. Just tap the brake and it reconnects the battery.

https://www.amazon.com/PriorityStart...a-570905062796

Not sure I'd want something like that. After a while the residual current will dissipate and the PCM will zero itself, and everything in the memory will be gone. At start-up the PCM will have to "relearn" everything. This could mean inefficient engine operation for up to 25 miles of driving.

[JoeInPA]

(sorry for the long post)
My truck (2006 Tundra 4.7 V8, 6500-lb. tow rating) does not have a dash button for towing mode. This is my first travel trailer (just brought it home yesterday). Coming home with the new, empty sub-4,000 lb. trailer, the truck did not seem to labor much at all on hills. Redline is 6K, and I don't think I ever saw RPMs go much over 4K to 4500 on moderate uphills, with normal flat road at highways speeds ~2200 RPM, going to ~3200 during downshifts at mild to medium uphill grades.

On the drive home - up and down some mountain foothills in central PA - I was leaving the truck in regular D-drive and manually turning off Overdrive from the button on the tree lever when in hilly areas, but leaving OD on for flat or mild downhill. My forward gear automatic trans options are 2, 3, D. The answers about overdrive in this and other older threads on the forum seem pretty much split, though a GM trans tech's reply from an older thread does carry more weight with me. I am thinking I should leave it out of OD entirely, and just eat the extra cost of gas in order to spare the expense and inconvenience of burning up the trans. What I am not sure of is whether I should be using D or 3 as my default gear when towing (other than very steep, slow grades, where I might need to use 2)?

Speaking of weight, we will be close to the towing weight limit on the truck once we are loaded for a trip. Trailer is just under 4,000 lbs. I'll have probably 900 lbs. in the actual truck (including humans), and maybe 200-600 lbs in the trailer, depending on if we need to fill the fresh water tank before we reach boondocking campsites. I know we should get a newer truck w/specific towing feature, but the Tundra has served our needs well, and I want to keep it until the wheels fall off.

[timfromma]

I had a Tundra once. The tow/haul button was on the end of the gear shift lever.

[phillyg]

No need to overthink it or buy a new truck. Leaving OD off is a bit like using a tow/haul mode. When climbing the transmission will automatically downshift, or you can gear down to keep your RPMs where it's not lugging the engine, or crazy high. When descending steep grades, start out slow and downshift manually if necessary to minimize using the brakes. I frequently disengage tow/haul on my TV on level ground if the RPMs stay where I want them and the engine is not lugging.

[Thomas ho]

tow haul on older trucks ,,,8/ 10 years old , tow-h. eliminates over drive . will drop down a gear or 2 on up hill if turned on under a load, automatically. older ford 98- up to ? year, turn on tow-h it will drop trans. down 1 or 2 gears . new chev. 2018 duramax 6.6 diesel tow haul mode truck must be 2/4 mph. turned on ,and +,-, switch changes gears with the +,-,button. just like a manual transmision. i have left so many toyota trucks way back behind me traveling , trds ,sequoias especially are very bad tow veh . even pulling a 18 ft .rv. a head wind of any amount .they are on i 40 texas barely at 55mph. i always say to myself "POOR LITTLE TOYOTA".

[JoeInPA]

Originally Posted by timfromma

I had a Tundra once. The tow/haul button was on the end of the gear shift lever.

That button on the end of the shift lever is labeled "Overdrive" in my truck, and pushing it displays a "OD OFF" indicator on the instrument cluster. I can't think of any significant reason for that function/button other than being synonymous with tow-haul situations. Seems only a semantic difference. Of course, I am not an engineer, so I could be wrong, but common sense tells me it's the same thing.

[AlaskaErik]

Originally Posted by JoeInPA

That button on the end of the shift lever is labeled "Overdrive" in my truck, and pushing it displays a "OD OFF" indicator on the instrument cluster. I can't think of any significant reason for that function/button other than being synonymous with tow-haul situations. Seems only a semantic difference. Of course, I am not an engineer, so I could be wrong, but common sense tells me it's the same thing.

Tow/Haul is not the same as OD Off. Tow/Haul resets the shift points. Depending on the vehicle, it can also lock out the upper gears, which is similar to turning OD off in your vehicle. Again, depending on the vehicle, Tow/Haul can also provide downhill speed control.

[Beachbourbon]

Originally Posted by JoeInPA

(sorry for the long post)
My truck (2006 Tundra 4.7 V8, 6500-lb. tow rating) does not have a dash button for towing mode. This is my first travel trailer (just brought it home yesterday). Coming home with the new, empty sub-4,000 lb. trailer, the truck did not seem to labor much at all on hills. Redline is 6K, and I don't think I ever saw RPMs go much over 4K to 4500 on moderate uphills, with normal flat road at highways speeds ~2200 RPM, going to ~3200 during downshifts at mild to medium uphill grades.

On the drive home - up and down some mountain foothills in central PA - I was leaving the truck in regular D-drive and manually turning off Overdrive from the button on the tree lever when in hilly areas, but leaving OD on for flat or mild downhill. My forward gear automatic trans options are 2, 3, D. The answers about overdrive in this and other older threads on the forum seem pretty much split, though a GM trans tech's reply from an older thread does carry more weight with me. I am thinking I should leave it out of OD entirely, and just eat the extra cost of gas in order to spare the expense and inconvenience of burning up the trans. What I am not sure of is whether I should be using D or 3 as my default gear when towing (other than very steep, slow grades, where I might need to use 2)?

Speaking of weight, we will be close to the towing weight limit on the truck once we are loaded for a trip. Trailer is just under 4,000 lbs. I'll have probably 900 lbs. in the actual truck (including humans), and maybe 200-600 lbs in the trailer, depending on if we need to fill the fresh water tank before we reach boondocking campsites. I know we should get a newer truck w/specific towing feature, but the Tundra has served our needs well, and I want to keep it until the wheels fall off.

200-600lbs in the trailer is a dramatic underestimate IMHO. Batteries, full propane, food, all the things your wife “needs”. Clothes, bedding, Your toys, etc…it all adds up quickly…Based upon experience, I would put you at 1000 lbs plus

[JoeInPA]

Originally Posted by Beachbourbon

200-600lbs in the trailer is a dramatic underestimate IMHO. Batteries, full propane, food, all the things your wife “needs”. Clothes, bedding, Your toys, etc…it all adds up quickly…Based upon experience, I would put you at 1000 lbs plus

I did not realize the dry weight of the trailer omitted the batteries. I can understand the 20lbs of propane (or whatever the weight is of the tank full v. empty). I was foolishly thinking ~200 lbs of "stuff" stowed in the trailer, plus a full 38-gal. fresh water tank ~300 lbs. - at least on part of the drive from the nearest water spigot to the boondock site. I will round it up to 1K lbs. Gotta say, though... this is not a huge camper. Even if we packed a TV (which I would prefer to not) along with kitchenware, canned food, beer, bottled water, clothes and toiletries, etc., It's hard for me to imagine going over 200 lbs. But, I am most definitely not a woman, and you are sure as hell right about that changing the calculus of what are "essentials." Could end up being 50 lbs of just shoes....

[ARhappycamper]

I tow in manual mode and tow/haul is not available. I also set the cruise and just use the +/- buttons to shift up and down as needed to keep the engine RPM in that sweet spot of maximum torque. It also keeps engine temps in check by shifting down whenever boost starts climbing upwards of 7 psi. I also like to let the boost go to around 12 psi up hills and mountains at 3-4K RPM, usually in 3rd gear. Yes, of course sometimes I must switch the cruise off for curves and very steep hills/mountains.