Transmission line pressure

[jltcasper3]

I have been wondering, Does anybody know what the tow haul button changes in the transmission line pressures wise, when you put it to tow haul mode? I heard somewhere that it increases line preassure, is this true. I know that tow haul changes the shift point a little. If it does increase line preassure wouldn't it be better to alwase to drive around in tow haul mode?

 

[Graphite 6]

Yes it does increase line pressure, but if you're asking from what psi to what psi, I'm sure someone knows here and will chime in. The down side to driving around in the tow/haul mode is you will never up shift to the point of using you're . 069 O/D while running down the interstate or back country roads. That said some drive around town with it engaged for better shift points in light to light kind of thing. There will be some fuel economy loss with the tow/haul always engaged. Hope this helps.

 

[bagd99dak]

somtimes i drive in tow/haul, and somtime i dont. the only difference i can actually feel is that the torque converter locks up on 3rd around 30-35mph. that is nice when towing my show truck around. other then that i dont notice any other drivabilty changes at all. and it still goes into overdrive at around 45-50 depening on how hard im driving it. i havent noticed any changes in the shift points with it on either.

 

[GaryCarter]

Yes it does increase line pressure, but if you're asking from what psi to what psi, I'm sure someone knows here and will chime in. The down side to driving around in the tow/haul mode is you will never up shift to the point of using you're . 069 O/D while running down the interstate or back country roads. That said some drive around town with it engaged for better shift points in light to light kind of thing. There will be some fuel economy loss with the tow/haul always engaged. Hope this helps.

Sorry, but you're wrong about that. T/H mode does not prevent shifting into OD.



Gary

 

[Bob4x4]

Driving to and from work I get better mileage in tow/haul



Bob

 

[Graphite 6]

Gary, Yes you are correct, I meant to say he wouldn't get the lowest RPM possible while crusing at hiway speeds rather than having it off. Thanks

 

[Bob4x4]

Gary, Yes you are correct, I meant to say he wouldn't get the lowest RPM possible while crusing at hiway speeds rather than having it off. Thanks

Under a light load I am in od/locked at 45 in tow/haul how can you get less rpm than that?



Bob

 

[DWBauer]

I use Tow/Haul almost all the time while driving around town. I get better fuel mileage because the torque converter is locked up sooner, as was stated in third gear at about 30-35 MPH. When on the short freeway sections I see no RPM difference between OD top gear when Tow/Haul is turned on then off. RPMs remain the same in top gear.

 

[cerberusiam]

I have been wondering, Does anybody know what the tow haul button changes in the transmission line pressures wise, when you put it to tow haul mode? I heard somewhere that it increases line preassure, is this true. I know that tow haul changes the shift point a little. If it does increase line preassure wouldn't it be better to alwase to drive around in tow haul mode?

The TH does not change line pressures. Those are set internally and can only be changed my modifying the pressure valve.



TH mode changes the operation of TV servo. What you get is more TV pressure at the same speed along with a more aggressive lockup strategy.



In stop-n-go driving TH mode is much harder on mpg than the normal mode. It takes more speed to make the shifts which means you use more throttle to get the speed.

 

[DGStrate]

Sorry, but you're wrong about that. T/H mode does not prevent shifting into OD.



Gary

Actually Gary,



Tow/Haul on the 3rd Gen, 03-04. 5s does prevent shifting into OD...



Tow/Haul on the 05s it does not prevent shifting into OD...



Tow/Haul on the 06s, you can push the button 1x or 2x - one of them engages Tow/Haul and the other Locks out OD...

 

[Bob4x4]

Actually Gary,



Tow/Haul on the 3rd Gen, 03-04. 5s does prevent shifting into OD...



Tow/Haul on the 05s it does not prevent shifting into OD...



Tow/Haul on the 06s, you can push the button 1x or 2x - one of them engages Tow/Haul and the other Locks out OD...

I beleive you will see that the truck has what is labeled on the shift lever. The 03 is labeled od off. the 05 is labeled tow/haul the 06 is labeled with both.



Bob

 

[Tmartin000]

I have a feeling that when the factory Jake is installed, I could swear it emulates the tow/haul mode... WITHOUT the light being on or the button switched.



Tom