Trucks & Trailers - Chevy 1500 Tow / Haul Mode Question

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rims421
03-05-2011, 06:20 PM
I have an 04 Chevy 1500 extended cab, long bed, 4wd pickup.
It is equipped with the factory tow package.
I just bought a Sea Hunt Triton 225 with a Venture tandem axle trailer with brakes on both axles. My question is regarding the use of the tow /haul button located on the shift lever.
What exactley does this provide.
It seems that it downshifts quicker and maintains the lower gear longer than it should.
Also when I am pulling the boat with the tow function off.The truck will feel like it is down shifting a 1/2 a gear when i approach an incline. In other words if I am approaching a hill and I gradually depress the accelerator it feels like the truck downshifts a bit and the rpms rise about 600 or so. With the tow function engaded in the same scenario the truck will downshift and the rpms will rise by about a 1000 or so. Sometimes this rise in rpms seems like it is more than I need for the circumstance.
What do you guys with a similar setup think about the tow / haul function on these trucks?


lemaymiami
03-06-2011, 04:27 AM
Here's the deal with that "tow/haul" switch... It only changes the shift points for your tranny to ease the strain that load is placing on it. You want you motor's rpms up a bit at slower speeds to keep from lugging with a heavy load behind you. Once you get up to highway speeds it's pretty much not a factor at all....

I'm running an '06 Silverado work truck with a 4.8 v-8 (the smallest eight they offered) and towing a fairly light, 2,000 total package day after day. I make a point of always having it in "tow/haul" mode when I'm towing my skiff. It's worked very well for me since I've been towing around 20,000 miles a year with it now for five years...

warfdog
03-06-2011, 11:39 AM
The GM 4L60E/4L65E transmissions in late model GMC/Chevy trucks are electronically controlled. According to the owners manual on my 2004 5.3L Yukon (4L60E) it changes the shift points and downshift programming to keep the trans in a lower gear longer, and to get it there sooner when slowing, it increases the internal hydraulic pressure to put more pressure on the clutch packs, and it changes the lockup point on the torque converter. You should see it downshift sooner, up-shift later, and hold gear longer plus shifts should feel more crisp.


Sailor
03-06-2011, 11:44 AM
^^What they said. I have also noticed that it increases MPG, although very slightly depending on the load, as the engine is in the correct torque range. Too low RPMs and you can do damage to the motor by lugging it.

twobyfour
03-07-2011, 04:01 PM
I have an 04 Chevy 1500 extended cab, long bed, 4wd pickup.
It is equipped with the factory tow package.
I just bought a Sea Hunt Triton 225 with a Venture tandem axle trailer with brakes on both axles. My question is regarding the use of the tow /haul button located on the shift lever.
What exactley does this provide.
It seems that it downshifts quicker and maintains the lower gear longer than it should.
Also when I am pulling the boat with the tow function off.The truck will feel like it is down shifting a 1/2 a gear when i approach an incline. In other words if I am approaching a hill and I gradually depress the accelerator it feels like the truck downshifts a bit and the rpms rise about 600 or so. With the tow function engaded in the same scenario the truck will downshift and the rpms will rise by about a 1000 or so. Sometimes this rise in rpms seems like it is more than I need for the circumstance.
What do you guys with a similar setup think about the tow / haul function on these trucks?

It sounds like its doing exactly what its supposed to. Keep on using it.

WolfLLY
03-08-2011, 02:45 PM
I have an 04 Chevy 1500 extended cab, long bed, 4wd pickup.
It is equipped with the factory tow package.
I just bought a Sea Hunt Triton 225 with a Venture tandem axle trailer with brakes on both axles. My question is regarding the use of the tow /haul button located on the shift lever.
What exactley does this provide.
It seems that it downshifts quicker and maintains the lower gear longer than it should.
Also when I am pulling the boat with the tow function off.The truck will feel like it is down shifting a 1/2 a gear when i approach an incline. In other words if I am approaching a hill and I gradually depress the accelerator it feels like the truck downshifts a bit and the rpms rise about 600 or so. With the tow function engaded in the same scenario the truck will downshift and the rpms will rise by about a 1000 or so. Sometimes this rise in rpms seems like it is more than I need for the circumstance.
What do you guys with a similar setup think about the tow / haul function on these trucks?




That 1/2 gear you feel, is the torque converter unlocking. You are going from a direct coupling to the engine, to a fluid coupling to the engine. Fluid coupling multiplies torque, but heats the trans fluid up fast, fast, FAST. Best bet is to leave it in tow haul when towing, as it does not unlock the converter so readily.

DeadWeight
03-08-2011, 03:52 PM
I also like hitting it when(i'm not towing) I'm going up a big hill with the cruise on. It keeps the truck from downshifting alot on the climb.

NEBassMan
03-08-2011, 04:29 PM
That 1/2 gear you feel, is the torque converter unlocking... but heats the trans fluid up fast, fast, FAST. Best bet is to leave it in tow haul when towing, as it does not unlock the converter so readily.

What he said.

You should also see a little more engine braking in tow mode.

rims421
03-09-2011, 04:27 PM
I thought the (1/2 gear) shift when accelerating might be the torque convertor.
I will be using the tow haul from now on for anything but flat ground.
If the truck needs to downshift it will be in tow / haul mode.
Hard to believe that the gas mileage is better too, but I am going to give it a try.
I drove 275 miles home with the rig completly empty ( most of the the way with tow/haul off) and got 10mpg. I tried to keep it around 60-65 but dropped under 60 on some pretty big climbs.
If I can get around 10 mpg when fully loaded using tow / haul model I would be very pleased.

2dogs1949
03-11-2011, 06:20 AM
With my 2006 Silverado 5.3 I get 11 -12 mpg towing my Mayvraft 1900. Loaded at about
3000lb. The Chevy mechanic told me with the weight of my boat, I don't need to use tow haul. This was the same mechanic that had just replaced my transmission because it was slipping and the torque converter was chattering.

lemaymiami
03-11-2011, 06:58 AM
You might want to find another guy....

As a guy that tows a lot (200 miles a day, roughly almost every day I'm booked) I keep the phone numbers of three different wrecker services in my cell (one for each county or contract area, including Everglades National Park) and have come home more than once on the back of a wrecker.... My current tow vehicle, '06 Chev Silv, 4.8L, is just over 120,000 and no sign of any tranny issues. My previous ride, an old Dodge Ramcharger, had to have the tranny re-built three different times (and I never got 30,000 out of any re-build). I'm sure the guys that re-build them know about this sort of stuff, but my current rig has been so reliable that I'll be looking for another one just like it (and following the owner's manual exactly when they say to use "tow/haul" when hooked up...).



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