ECT or S4 when pulling trailer

Frequently pull a 6x12 utility trailer with 60 inch zero turn mower. Mostly short stop and start trips. What would be best setting ECT on,S4 or would D be sufficient ? Been using S4 and getting less than 12 MPG .

 

When towing anything it’s best practice to lock out the overdrive gears. S4+ECT is a good way to go. If you decide to tow in D keep an eye on your tranny temps. If you get gear hunting or excessive TC unlocking you’ll want to switch to S4.

 

I agree for significant towing s4. For a mower only thats your judgement. If truck pulls it and does not seak gears do whatever. For a 3rd gen id likly use s5 and see how it does. With real weight or an air wall. S4 just smarter.

 

Read. The. Manual.

Ect + S4 for towing.

 

Yes, both.

 

That's the life of towing with a Tacoma.

 

Your truck should have come with an Owners Manual. If not hit up the dealer for one. S4 and ECT.
Fwiw, I towed a 3300 lbs Coachmen Nano 187 and get 14 mpg. I have a mid rise topper which added abut 2.5 mpg because of improved aerodynamics when trailering.

 

For those of you saying the manual states ECT and S4, are you referring to a 2nd gen V6 auto?

I don’t see that requirement in the manual for the 3rd gen 6 speed auto. Only reference I see in the manual says to “maintain engine braking and charging efficiency performance use S5 or lower.” The manual also states to use ECT when “high levels of response or feeling are desirable,” but does not require it.

Personally, I find towing more relaxed in S5 with ECT off. I monitor trans temp with Scangauge II and towing temps typically range between 160 and 180 deg F, with no hunting. When terrain warrants, I manually downshift to keep the torque converter locked and temps down.

Please let me know if I misread or missed something in the manual.

 

2nd gen doesn’t have ECT or S mode. Common practice with 2nd gen is to set it to 4th and give ‘er.

 

where are you located? Some of our answers are relative to where we live. Here in the Rocky Mountains, my unloaded 1st gen had to stay in 2nd to make it up some passes at 50mph... my supercharged 2nd gen can stay in 5th gear and still accelerate up the same pass and keep trans temp around 150.

If you’re in the dust bowl, I wouldn’t be surprised that S5 with no ECT would be fine on calm, non-windy days.

 

Basically, if the torque converter will stay locked in your towing situation, you’ll be fine. Otherwise, downshift a gear in Sport mode until the trans temps stay consistent.

 

Sharpest and Jason,
Thanks for your responses and clarifications.

I live in the Southeast and it is mostly flat to rolling terrain. Whenever, an elevation rise is about to unlock the torque converter, I manually downshift to keep it locked and I see no increase in temps.

We do plan some trips to real mountains post-COVID, so expect I will spend more time in lower gears. Looking to install trans cooler as I understand the torque converter does not lock up in some of the lower gears. Trying to do some research on the AC60 transmission to confirm that.

 

Not 100% on this but I would guess lockup is only in 4/5/6. 4th would be your straight 1-1 gear and 5/6 are overdrive gears. I would set it to 4th and forget about it unless RPM exceeds 3000, in which case I would slow down or possibly select 5th.

 

What is the top speed for S4? I usually cruise with my camper around 70mph. Is that too high for S4?

 

Is there a max speed for S4?

 

Won't hurt anything but your mileage. Other safety factors come into play way before you start endangering your transmission.

 

S4 is totally fine at 70 mph. But if you're towing drop it down to 55-60 and watch your mileage actually be decent.

 

With my 2022 Tacoma SX Access cab 3.5 V6, I don't use ECT at all, just S4 and it hums without searching for gears. Of course I only pull a 2900 lb travel trailer. I'm going to do some experimenting with S4 with ECT on and see if I get better gas mileage. Right now between 14 and 16.

 

I've done that experiment. It's marginal, and it's very difficult to get above a 15 mpg average when towing at highway speeds. That's about where I'm at also.

ECT is really only there for acceleration assistance. It delays the upshift so that the engine is working in it's power band when you need it.

Good MPGs come from the ability to maintain a constant load on the engine. (Less stop/go, more smooth cruise). So during the times you're contributing to a good average, the truck isn't shifting. Milage wise, for the most part it doesn't matter if ECT is on or off.

...For the most part. There's an exception to what I just claimed. If you're in rolling hills and trying to maintain a constant instead of playing the momentum game of letting gravity scrub or contribute to your speed, then it's marginal improvement with ECT off. Marginal. The reason is that ECT will be quicker to downshift and slower to upshift in hills than normal mode. But you're not making huge gains in that timeframe when comparing the two side by side.

I didn't see a huge enough difference to keep it off. I leave mine on when towing.