"Tow Mode" - Does anyone have real, technical info on what it does?

[itsjustme]

I've read the manual, which basically says "when towing use this, it helps". gee, thanks.

I know it changes shift points and more importantly, adds some kind of hysteresis to hold gears.

but does anyone have a more comprehensive definition of what it does?

TIA,

G

 

[JF19Longhorn]

More engine braking by downshifting sooner, less heat due to holding lower gears longer, it might mess with the pedal maps (not sure if RAM does this), might also delay/disable MDS.. I'm sure there is more, all I can think of off the top of my head.

 

[SpeedyV]

Disables MDS, disables Aero Mode, disables Stop/Start, changes shift points...but no, I don't have technical information on this.

 

[Dusty1948]

Unlike the old printed service manuals that went into detailed operation description, the new electronic service documentation does not include a operation description. Apparently that info is now found in the training manuals only.

From the DT service manual on when Tow/Haul is selected:

1. The Tow/Haul indicator lamp will illuminate
2. MDS is not available
3. Transmission will not shift into 8th gear
4. Upshifts will be delayed in all forward gears
5. Tow/Haul mode not available in Four Wheel Drive Low
6. Selecting Hill Descent Control (HDC) will disable Tow/Haul Mode. Selecting Tow/Haul Mode will disable Hill Descent Control.

Past Chrysler design methodology included eliminating Electronically Modulated Converter Clutch (EMCC) control and altering the operation of the torque converter engagement when in the Tow/Haul Mode. I looked at the 8HP75 power flow charts and diagram and cannot see where any torque converter, or for that matter any clutch operation, changes with selecting the Tow/Haul mode.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 042595 miles.

 

[JMD227]

I really wish we could activate some of these features, but not all. I want to cruise in 8th with MDS, but have the change in shift points.

 

[YawnY]

Worked at dodge, and did their transmission course. Alot is correct about holding gears and shift points, but it also increases the fluid pressure to the different circuits in the transmission to ensure the gears hold and reduce slippage.

 

[bhurst10]

The statement is disables MDS is not correct i have towed with my 1500 Limited 5.7 Non E-torque 392 gears amd seen my MDS come and off I was only towing about 6500 lbs but I have seen it,

Sent from my SM-T720 using Tapatalk

 

[HemiDude]

Disables MDS, disables Aero Mode, disables Stop/Start, changes shift points...but no, I don't have technical information on this.

Disables aero mode? Curious why Ram would choose this as necessary. Seems like we can use all the "aero" we can get when pulling a big load

 

[bazbob]

Disables aero mode? Curious why Ram would choose this as necessary. Seems like we can use all the "aero" we can get when pulling a big load

Here's the thing with Aero mode, Tow/Haul disables the automatic change from normal to aero at maintained speeds above 62mph (or whatever triggers it for you). The reason is that changing your ride height impacts weight distribution when towing. There's nothing that prevents you from manually changing to Aero mode or back to normal at highway speeds. I use this all the time when towing as I can feel WD shift to the front axel when lowering the air by that 6/10ths of an inch. The point here is that Tow/Haul respects the established ride height and it will require manual intervention to change it.

 

[JF19Longhorn]

Unlike the old printed service manuals that went into detailed operation description, the new electronic service documentation does not include a operation description. Apparently that info is now found in the training manuals only.

From the DT service manual on when Tow/Haul is selected:

1. The Tow/Haul indicator lamp will illuminate
2. MDS is not available
3. Transmission will not shift into 8th gear
4. Upshifts will be delayed in all forward gears
5. Tow/Haul mode not available in Four Wheel Drive Low
6. Selecting Hill Descent Control (HDC) will disable Tow/Haul Mode. Selecting Tow/Haul Mode will disable Hill Descent Control.

Past Chrysler design methodology included eliminating Electronically Modulated Converter Clutch (EMCC) control and altering the operation of the torque converter engagement when in the Tow/Haul Mode. I looked at the 8HP75 power flow charts and diagram and cannot see where any torque converter, or for that matter any clutch operation, changes with selecting the Tow/Haul mode.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 042595 miles.

I'm pretty sure mine shifts into 8th while towing in T/H mode.

 

[silver billet]

The statement is disables MDS is not correct i have towed with my 1500 Limited 5.7 Non E-torque 392 gears amd seen my MDS come and off I was only towing about 6500 lbs but I have seen it,

Sent from my SM-T720 using Tapatalk

Nope, it definitely disables MDS in my truck. I've tested this extensively; cruising down a rural road at 50 mph, no wind, no towing, no weight in truck, just me. MDS kicks in of course. Flip TH, instantly MDS goes off. Flip it off, MDS comes back on. Like clockwork, 10 times in a row.

If you want me to provide a video, I'd be happy to try and create one. Otherwise, I'd be interested if you could do the same test, perhaps we're not all running the same software and it works differently.

But I suspect you didn't have MDS come on while towing 6500 pounds. Most trucks turn off MDS with 0 load attached on a straight road with just a bit of head wind hitting them. 6500 pounds is a very heavy load, my truck runs in 6th gear towing 5000 pounds, there is absolutely no way MDS is getting activated, in any gear, at any speed, while towing that kind of load. It just can't run on 4 cylinders while doing that.

 

[SpeedyV]

Nope, it definitely disables MDS in my truck. I've tested this extensively; cruising down a rural road at 50 mph, no wind, no towing, no weight in truck, just me. MDS kicks in of course. Flip TH, instantly MDS goes off. Flip it off, MDS comes back on. Like clockwork, 10 times in a row.

If you want me to provide a video, I'd be happy to try and create one. Otherwise, I'd be interested if you could do the same test, perhaps we're not all running the same software and it works differently.

But I suspect you didn't have MDS come on while towing 6500 pounds. Most trucks turn off MDS with 0 load attached on a straight road with just a bit of head wind hitting them. 6500 pounds is a very heavy load, my truck runs in 6th gear towing 5000 pounds, there is absolutely no way MDS is getting activated, in any gear, at any speed, while towing that kind of load. It just can't run on 4 cylinders while doing that.

Agreed. I tested this and could not even get MDS to engage on an extended off ramp (coasting from 70 down to a stop over about a 1/2-mile). There's no way MDS wouldn't engage in that situation if permitted.

 

[itsjustme]

Disables MDS, disables Aero Mode, disables Stop/Start, changes shift points...but no, I don't have technical information on this.

Actually, that's all pretty useful stuff (to me). MDS and start/stop are not two of my preferred features. And holding gears a bit longer, while a bit less economical re: fuel, results in lower stresses on movngs parts. Might just become my normal driving mode; much like "sport mode" in older Porsche _programmed Tiptronics. Thnx.

You are fairly certain on those?

 

[SpeedyV]

Absolutely...and the truck feels like a beast when running around in Tow/Haul mode unloaded.

 

[bill-e]

I'm pretty sure mine goes into aero mode when tow/haul but I cant confirm until the spring.

 

[itsjustme]

The statement is disables MDS is not correct i have towed with my 1500 Limited 5.7 Non E-torque 392 gears amd seen my MDS come and off I was only towing about 6500 lbs but I have seen it,

Sent from my SM-T720 using Tapatalk

How does one "see" MDS it come on? I don't see any obvious indication. I'm also curious why it would go into 4 cyl mode with 6500 lb behind it. That seems odd to begin with.

 

[JF19Longhorn]

How does one "see" MDS it come on? I don't see any obvious indication. I'm also curious why it would go into 4 cyl mode with 6500 lb behind it. That seems odd to begin with.

Eco light comes on