When towing stuff is it recommended to turn O/D off and turn ECT on?

geigerz2001 · Apr 21, 2010

I am going to the desert to play in the sand and will be towing some quads on a trailer from a rental place. Is the consensus to turn the O/D off and turn on the ECT? Truth is I've never used those functions so I am clueless as to what they are for.

Thanks

96743runner · Apr 21, 2010

It probably would be a good idea to turn the O/D off. Less stress and less heat for the transmission. Turning O/D off will keep the transmission from shifting into overdrive (4th gear). Don't know if turning on ECT will help or not (ECT makes the transmission shift at higher RPMs)

peter78 · Apr 21, 2010

geigerz2001 said:
I am going to the desert to play in the sand and will be towing some quads on a trailer from a rental place. Is the consensus to turn the O/D off and turn on the ECT? Truth is I've never used those functions so I am clueless as to what they are for.

Thanks

Yes, I put them both on. The ECT will make the transmission shift at a higher RPM and if you have a trailer on the back, that should help. I don't go fast, but go smoothly through the gears. When it shifts between say 2nd to 3rd gear, the RPM will be slighter higher in the beginning of the 3rd gear and will take less strain for the transmission, especially if your towing a heavy trailer.

The biggest problem with towing is having the transmission oil gets too hot. The biggest build up of heat, is when you have the overdrive on. Having a transmisson cooler can help, but keeping it out of overdrive really does help. 3rd gear is 1:1 ratio, meaning there is no overdrive. With my 2,100 pounds trailer I sometimes still use the overdrive, but I make a point of turning off the overdrive every so often, so I can cool the transmission.

A lot of what you might want to do will depend on the terrain and the wieght of the trailer.

brian2sun · Apr 21, 2010

Generally you would want to tow with the O/D off. The ECT button hardly makes a difference, but I would leave that on. As far as the O/D goes, I say "generally" because you want to leave it off for hills and slower speeds, but if you're on a long flat road and aren't struggling for power, turn it on so you don't scream down the highway at 3500 rpms at 60 mph. You'll just waste a lot of gas if you drive over 55 on flat roads with O/D off.

geigerz2001 · Apr 23, 2010

Thanks for the help guys!

Thanks

bass-o-matic · May 8, 2018

Hello Old Thread.

I've been towing with my ECT off. Never realized I should turn it on. I've probably gone a 1000 miles... with a 2800 lb trailer. I do have a tranny cooler and rarely go over 200f. Always keep OD off.

I guess...I shouldn't worry... and should now start turning on ECT?

eh?

Ok, I'm bored.

jgue467 · May 8, 2018

ECT does interesting things. The most obvious, that Everyone seems to know is it adjust shift points slightly higher allowing for a "performance" mode of sorts for the ol' 3.4.

But few on here mention what else it does, at speed.

Once up to cruising speeds, with ECT on, the slightest depresses of the throttle and/or slightest hills cause downshifting (as vehicle slows while climbing with same amount of gas pedal pressure). If the terrain is fairly level, downshifts maybe annoying and a little fuel inefficient.

I've learned I get every so slightly better fuel efficiency with ECT off, the "performance" of the runner to me is virtually the same and I don't like winding the ol' 3.4 up much beyond 3500rpms anyway.

Anyway that's how I sum up ECT. Luck and enjoy. :cowboy:

absalom · May 8, 2018

One thing that has always confused me is recommending O/D off when towing. Doesn't TC lockup in O/D? And isn't this where you'd see your lowest temperature?

I understand that higher RPM's create a closer ratio fluid coupling, but it seems to me that a locked TC will generate lowest possible temps for the work being demanded.

I recall my 4th gen owner's manual specifically instructs drivers to leave the trans in D when towing, saying that the car will decide the appropriate gear for the driver.

Thoughts?

Edit: Yup, just as I thought -- the 3rd gen owner's manual give the same advice. O/D on and trans in D.

I'm not saying the forum is wrong and Toyota is right. But has anyone actually confirmed that towing with O/D off actually lowers temps? Or is this just something we all reflexively regurgitate when someone asks about towing?

Upon further reading of the manual, Toyota makes it sounds like the sole purpose of different choices for gearing (including O/D) is for engine braking, which makes sense.

jgue467 · May 8, 2018

absalom said:
One thing that has always confused ...

But has anyone actually confirmed that towing with O/D off actually lowers temps? ...

I had my runner bypassed for a few years then added torque.

I discovered whether towing anything or not, trans temps rose to over 245 when OD remained on during mountain pass or multiple hill climbs.

Turning OD off, lowered trans temps to around 200 in the same conditions within 30 seconds.

Then I replaced radiator and connected external cooler through it. Temps won't climb as high with OD on but still can reach 210 if I don't utilize OD off on the bigger climbs. That's my experience, who's next? :cowboy:

spartacus · May 8, 2018

When climbing with O/D on there is a a lot of gear hunting which creates more heat in the trans with O/D off the torque converter locks into 2nd or 3rd and trans temps drop. but if I am driving on a long stretch of flat road I turn the O/D on lower the rpms and there is no gear hunting and lower A/T temps. going down hill on 7% grades keep it in 3rd or 2nd depending on speed with overdrive off

pressing the ECT button turns on the power mode and the upshift in the power mode will occur later, at a higher speeds. For example, an upshift to third gear at 50% throttle will
occur at about 37 mph in normal mode and about 47 mph in power mode.

phattyduck · May 8, 2018

absalom said:
One thing that has always confused me is recommending O/D off when towing. Doesn't TC lockup in O/D? And isn't this where you'd see your lowest temperature?

The torque converter locks up in 3rd gear if OD is off. It also locks at a lower speed (around 45mph instead of at least 55mph) and it locks and stays locked at much higher throttle openings.

Towing with OD on often causes the torque converter to unlock in 4th/OD, and even if the trans downshifts to 3rd the torque converter will stay unlocked in situations when it would lock if the OD was disabled.

I leave OD on for my 4'x8' utility trailer unless it is heavily loaded, but with larger/heavier stuff I turn it off.

The most recent fun trip was this:

Just over 3k lbs (weighed) total. Trans temps maxed around 210*F with no supplemental cooler.

-Charlie

DK327 · May 9, 2018

jgue467 said:
That's my experience, who's next? :cowboy:

For the past couple of years I've been taking an annual trip from Omaha, NE to Custer, SD around Memorial Day when the temps are nice and warm. Climbing from 1000ft elevation to 5000ft as I near my destination, I've noticed if I have the OD on, the trans regularly hovers around and often surpasses the 200F mark, even with an inline trans cooler. If I have the OD off, the trans temp usually stays even with the engine temp (~190F) and when it does dip above 200F, cools down much faster after the climb. That's been my experience both times so far.

WayneM · Feb 16, 2025

Today, I (2001 4R Ltd) needed to tow a load (about 4000# total) over a pass. About 2000' elevation change in 5 miles, smooth pavement, 40-50 mph going up.

With O/D On, at these speeds, it would mostly be 3rd with some downshift to 2nd.
I wanted to prevent 4th, so I turned O/D Off. When I did that, the 2nd/3rd shift point *lowered*. It actually reduced the rpm/speed at which it would upshift to 3rd very significantly.

That's confusing to me:
1. I thought O/D On simply enables 4th.
2. I didn't think O/D changed shift points for 1-2 or 2-3.
3. And, even if it did, why would it reduce the 2-3 shift point rpm?

Is there something wrong with my O/D operation?

PS. The numbers above are approximate. It's a very heavily used semi-highway.
PSS. I totally forgot I had ECT. It was Off the whole time.

jgue467 · Feb 16, 2025

Mine does the very same so it is normal.

Bottom line I only turn OD Off when I am already in 4OD at highway speeds and starting to climb then i hit the OD and it drops it into 3rd locked (no slipping = far less heat).

That is the only situation I find OD Off useful for as they implemented it back then.

WayneM · Feb 17, 2025

Thanks jgue467 for the confirmation. Weird, but I won't worry about it.

phattyduck · Feb 18, 2025

WayneM said:
Is there something wrong with my O/D operation?

Are you possibly confusing the 3rd-unlocked to 3rd-locked transition with the 2-3 shift? It will lock the torque converter earlier and more aggressively (allow more throttle before unlocking) with O/D Off selected.

-Charlie

WayneM · Feb 18, 2025

Charlie, That is certainly possible. I've never paid attention to 3rd lock/unlock, and almost always leave O/D On.

What surprised me is that I was climbing with O/D On somewhere in that 40-50 mph range at 3000 rpm (just a guess, I don't actually remember). Then, I switched O/D Off, and the rpm dropped to 2000 rpm (another guess). I'm not sure of the numbers, but most definitely a significant drop in rpm.

So, in that situation, O/D On seemed better for pulling the load than O/D Off.

Should I have used ECT, or manually select 2nd? Maybe... Next time I'll have more thoughts to try.

phattyduck · Feb 19, 2025

WayneM said:
Charlie, That is certainly possible. I've never paid attention to 3rd lock/unlock, and almost always leave O/D On.

What surprised me is that I was climbing with O/D On somewhere in that 40-50 mph range at 3000 rpm (just a guess, I don't actually remember). Then, I switched O/D Off, and the rpm dropped to 2000 rpm (another guess). I'm not sure of the numbers, but most definitely a significant drop in rpm.

So, in that situation, O/D On seemed better for pulling the load than O/D Off.

Should I have used ECT, or manually select 2nd? Maybe... Next time I'll have more thoughts to try.

2nd at 40-45 would be 3500+ RPM - you were likely in 3rd. The drop to a locked torque converter is probably more like 300-400 RPM under load like that. It is much better for the torque converter to be locked, since otherwise an open torque converter creates a LOT of heat under sustained loads like that.

With this generation 4Runner, it won't lock the torque converter in anything but the top gear (3rd or 4th, depending on O/D selection) and at sufficient road speed (around 40 in 3rd or 50 in 4th, but varies with gearing). Hopefully you have a good cooler on there and are watching trans temps...

-Charlie

When towing stuff is it recommended to turn O/D off and turn ECT on?

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