Tow Haul button does nothing

[SnoKing]

I use mine a lot. Every day that I drive in or out of the summer park that has a 5 mph limit, I lock it in first gear. Going down grades I will manually shift to a lower gear on the exhaust brake.

 

[RVTRKN]

More than likely the dealer reset it, either knowingly or not, when they connected up to their computer. The electronics on the new trucks are fickle, and after an update in 09 at dealer for my 07 C&C, I've had a glitch. They denied it, and I didn't push it. After warranty, I regretted it. I would keep it in T/H for a long period to make sure it doesn't come back.

 

[Wiredawg]

I use mine a lot. Every day that I drive in or out of the summer park that has a 5 mph limit, I lock it in first gear. Going down grades I will manually shift to a lower gear on the exhaust brake.

With 4.88s on my truck it won't upshift out of first at idle. While towing, I just tap brakes on the downhill that downshifts with full EB.

I understand there's differences between load, gearing, trans programming, engine performance, and driving style. I see huge differences between how my 2017 Ram 5500 prforms and my former 2009 Ram 4500 with 4.44s and I was running Smarty on level 5 all butthe first 4 months I owned that truck. 2017 much more capable.

And, NOW 2019 Ram 3500 max tow rated 43K Lbs GCWR. WOW.

Anyway, it's always interesting to hear how folks use their trucks.

Cheers, Ron

 

[Rand Kibodeaux]

More than likely the dealer reset it, either knowingly or not, when they connected up to their computer. The electronics on the new trucks are fickle, and after an update in 09 at dealer for my 07 C&C, I've had a glitch. They denied it, and I didn't push it. After warranty, I regretted it. I would keep it in T/H for a long period to make sure it doesn't come back.

Well something definitely happened at the dealership. I keep finding out new things that the transmission would not do before. Yesterday I noticed that it would actually drop a gear when engaging tow/haul at 40 mph, while not towing and on level roads. I also noticed for the first time yesterday that tow haul mode was shifting at higher rpms. That’s the one feature of the tow mode everyone was talking about that I really wanted to experience firsthand. And now it finally works. I keep reading that the transmission “learns” driving habits. That’s some high tech voodoo stuff that baffles me. Now I’m very curious to see how the truck performs while towing. I know 4K is not a lot of weight to tow, but previously the truck just refused to downshift in tow mode on steep grades unless I stuck the gas pedal to the floor.

The build date on the truck was May 2018, and I bought it new in May of this year. It had 6 hours of idle time on the motor and 8 miles on the odometer when I bought it. Maybe the transmission didn’t “learn” diddley squat during intermittent idles for the first year of its life.

 

[Wiredawg]

Tow haul I a wonderful feature.... on my 03 2500 48RE all it did was lock out overdrive. Now, its completely separate programming that really enhances towing performance.

Glad you got it working.

Cheers, Ron

 

[WalterJ]

To me this is the most noticeable difference between the two tow haul modes. It also won't shift as casually with the TH on, meaning it shifts at a noticeably higher RPM than with it off.

Yup, that's what I would want...my {old} truck stays in a lower gear with TH 'cause it's purrfect for driving in town with lower speed limits or hilly country/county roads. I'm thankful for those intelligent engineers drive train decisions.

 

[Wiredawg]

It's funny how different folks have different experiences, although ALL things NOT the same. My 2017 Ram 5500 with 4.88s performs VERY well with JUST full EB. Special programming on my MAX TOW make TH too aggressive with my ratio. EB full stays on ALL the time and on the C&Cs, it STAYS on at startups. Just a LITTLE perk, but a nice one.

BUT, TH and EB towing heavy is SWEET in town and low speed. Just sharing another experience.

Cheers, Ron

 

[SnoKing]

EB only with my 3.42 gears comes on and off while slowing down through the gears like on a freeway off ramp(I would call it lazy at best). Add TH and it stays on and the truck shifts down aggressively.

 

[Wiredawg]

EB only with my 3.42 gears comes on and off while slowing down through the gears like on a freeway off ramp(I would call it lazy at best). Add TH and it stays on and the truck shifts down aggressively.

Sno,
I think we're pretty close. I like coasting in town when I see traffic ahead OR red light in the distance with transmission in normal mode. Letting foot off accelerator allows gradual slowing AND touching the brake gets EB. TH AND EB no real coasting on mine. Aside from so called "Special Transmission Programming" listed under Max Tow, i think the biggest difference is gear ratios. 4.88s are huge difference over 3.42s and 4.10s. Not as much over 4.44s, but still some. Not a big difference on tire height in the calculation.

Cheers, Ron

 

[RVTRKN]

C&C's have a different program and may even have a different Aisin trans, I know it used to be. I didn't like the T/H feature when I test drove a 07 C&C with the Aisin, before I chose the G56 in 2007.

 

[kthaxton]

EB shuts off at around 1100 rpms. So, if you are not in TH, the trans is not downshifting automatically when you are slowing down, therefore 1100 rpms is going to be reached much quicker and EB is going to disengage.
When in TH, the trans begins downshifting as you slow thus staying above 1100 rpm utilizing the EB much longer.

Also, as Wiredawg said, a lower gear ratio is going to make the EB much more effective and keeps the rpm's higher at any given speed which keeps the EB engaged longer, or more specifically, to a slower speed than a higher gear ratio.

 

[WalterJ]

EB shuts off at around 1100 rpms. So, if you are not in TH, the trans is not downshifting automatically when you are slowing down, therefore 1100 rpms is going to be reached much quicker and EB is going to disengage.
When in TH, the trans begins downshifting as you slow thus staying above 1100 rpm utilizing the EB much longer.

Also, as Wiredawg said, a lower gear ratio is going to make the EB much more effective and keeps the rpm's higher at any given speed which keeps the EB engaged longer, or more specifically, to a slower speed than a higher gear ratio.

Under about 1300-1400 rpm, my EB drops out because LockUp drops out, so that's when EB is NOT engaged; makes sense for my '04.5 anyway.

 

[Rand Kibodeaux]

As a follow up, last month I made a 2000 trip while towing. The tow haul feature worked very well. I did find another use for it in the hot summer heat. On 100 degree days, driving around town, I use the tow haul feature to get a few more rpms out of the engine at speeds under 45 mph. It spins up the air conditioning compressor a little more and cools the cab quicker.

 

[RVTRKN]

With my new 2019, I keep 4th at the highest gear when in city, not just for AC, but keep the RPM’s where they should be.

 

[AH64ID]

I’m not sure rpms matter that much for the compressor, as at slow speeds the limitation in the condenser and not the compressor. The fan programming on my ‘18 is pretty aggressive at low speeds for the AC, and I haven’t found a need to limit gears when empty for any reason other than short/steep rolling hills. Now I don’t get Vegas/PHX hot, but it gets hot here.

 

[RVTRKN]

I use the high idle feature for AC, you need the compressor running double of idle RPM, to keep the refrigerant moving heat out of the Cab. High temperatures absorbed in refrigerant through the evaporator, needs to be moved faster. Vegas/Phoenix heat is an issue, and running higher RPM’s makes a big difference you can feel, not just imagined.

 

[SnoKing]

I use the high idle feature for AC, you need the compressor running double of idle RPM, to keep the refrigerant moving heat out of the Cab. High temperatures absorbed in refrigerant through the evaporator, needs to be moved faster. Vegas/Phoenix heat is an issue, and running higher RPM’s makes a big difference you can feel, not just imagined.

That is strange, as I routinely sit in parking lots with engine idling in East Valley of Phoenix in pretty warm weather while wife runs in a store and the AC is pumping out nice cool air.

 

[Wiredawg]

RV and Sno,

I've had pretty good experience runn AC at idle, but old school me remembers old issue where idling caused fuel wash in cylinders. I imagine AC compressor may put enough load on engine to not, but just old TYPE A me, I idle up to around 1200 to 1500 RPMs. I know cooling the truck down before shut down with AC on I see 400° at EGT1 which translates to about 600° at the manifold. That's reason I want to install my free EGT probe into the exhaust manifold so I can see the real number.

I see this as another not really right or wrong procedure, just what WORKS for each of us.

Good discussion!

Cheers, Ron

 

[AH64ID]

I know cooling the truck down before shut down with AC on I see 400° at EGT1 which translates to about 600° at the manifold.

I think you be surprised when you get the probe installed.

I ran pre and post pyro’s on my 05 and the temperature difference was almost always 10° per psi of boost, and with a variable turbo I expect it to be even more consistent. Often at idle post was higher than pre, as the exhaust was pulling heat out of the turbo. It would take a long time idling for post to be below pre, and never by 200°, even at 1200-1500 rpms no load.

EGT1 reads a lot like the post reading on my 05.

 

[RVTRKN]

I’ll bet you were already cooled down and just maintaining temps when at idle. Start with a cab at 110* and see how well it cools off at idle only