Downshift & Deceleration at 32 to 23 MPH

[MICA4R]

Has anyone other than me noticed a downshift and deceleration when the truck is coming to a rolling stop (no brakes) from any speed above 35 mph? Trasmission engages during coasting in the range of 32 mph to 23 mph. It seems like the transmission downshifts/engages at 32 and then disengages at 23 in effect causing engine braking. Also, I can see the the rpms bump up a little in that range and then from 23 mph to 0 mph rpms drop?

Ive checked this on multiple inclines and road conditions it seems to be consistent which is good, but still makes me wonder if there is a way to reset this or disable it.

 

[morphius909]

Has anyone other than me noticed a downshift and deceleration when the truck is coming to a rolling stop (no brakes) from any speed above 35 mph which engages during the range of 32 mph to 23 mph. Is seems like the transmissions downshifts/engages at 32 and then disengages at 23 in effect causing engine braking. Also I can the the RPM bump up a little in that range and the after 23 mph to 0 mph rpms drop?

Ive checked this on multiple inclines and road conditions it seems to be consistent which is good, but still makes me wonder if there is a way to reset this or disable it.

Yes, same here. A little annoying but i believe it is normal.

 

[swingbatta]

My 07 Sport does this also.

 

[Acidmeld]

Its normal and built into the valve body. Cannot and should not be disabled.. Its just there to keep from accelerating downhill.

 

[MICA4R]

Its normal and built into the valve body. Cannot and should not be disabled.. Its just there to keep from accelerating downhill.

I see, so the valve body is a structural part of the transmission body? The downshifting occurs on flat surfaces and therefore I'm assuming it is not incline dependent. It robs a little bit of fuel economy. ( irony is that I have a 4.0L engine and I'm concerned about fuel economy )

-thankx

 

[ALLEGRO]

I have also noticed that when at highway speeds and going down a significant decline, the torgue converter will lock back up and along with the tranny it will act as an engine-brake to keep from accelerating down the hill.

I noticed this several times on the same decline over the Christmas season.

 

[MICA4R]

bump

 

[KB084RUNNER]

If you keep light pressure on the accelerator pedal the trans will not downshift as the ETC tells the trans you are not in braking mode. If you let off the throttle or touch the brake the trans ecm will downshift. Try it going downhill...just keep the weight of your foot on the gas pedal and it should not downshift.

 

[Jerrydog]

My new to me 2005 does this as well and I find it annoying...

 

[03_4x4Runner]

I live in a mountain area and this feature really saves brakes going down hill. It maintains my downhill speed without riding the brakes. I put the shifter in the 4 position, when the speed creeps up down the hill tap the brakes lightly, this locks the torque converter to let engine braking work. It remains locked untill the gas pedal is hit again. I love this feature. It does not acctually shift to a lower gear it just locks up the torque converter.

 

[Kmvreter]

I live in a mountain area and this feature really saves brakes going down hill. It maintains my downhill speed without riding the brakes. I put the shifter in the 4 position, when the speed creeps up down the hill tap the brakes lightly, this locks the torque converter to let engine braking work. It remains locked untill the gas pedal is hit again. I love this feature. It does not acctually shift to a lower gear it just locks up the torque converter.

I want to try and replicate this. What speed range are we talking (same as the OP relatively slow or highway speed) and approximately what grade (long slope or steep)?

 

[Jerrydog]

I live in a mountain area and this feature really saves brakes going down hill. It maintains my downhill speed without riding the brakes. I put the shifter in the 4 position, when the speed creeps up down the hill tap the brakes lightly, this locks the torque converter to let engine braking work. It remains locked untill the gas pedal is hit again. I love this feature. It does not acctually shift to a lower gear it just locks up the torque converter.

I'd rather put the wear and tear on 10 sets of brakes than transfer it to the drivetrain. Naturally Engine braking is important sometimes but in daily driving rarely unless you live in the mountains. Said another way I'd rather this was optional and save my engine and tranny and not the inexpensive brakes.

 

[03_4x4Runner]

I want to try and replicate this. What speed range are we talking (same as the OP relatively slow or highway speed) and approximately what grade (long slope or steep)?

I am genereally going 35 mph. That is the speed limit in most of the area where I live. It is very noticable to me. Generally long slopes but I take it out of 5th gear and put it in 4th. It does not work well in 5th. I am up and down hills all the time in town so I just leave it in 4th unless I am on the highway. If you are going down a grade, lightly tap the brakes but do not really apply them, you should feel a slight shift of the torque converter loccking up, if this slows you down to much lightly touch the gas pedal and you will feel the converter unlock and you will gain speed. As far as the comment from Jerrydog about durability I do not think Toyota would put in this feature if it was going to cause damage. The torque converter lock and unlocks all day long even in normall driving. Mine is 8 years old mostly all in the mountains and has never had a problem. Around here you follow people going down long grades for a mile or so lightly riding the brakes the whole time to maintain speed. That seems much more damaging to me.

 

[Jerrydog]

I am genereally going 35 mph. That is the speed limit in most of the area where I live. It is very noticable to me. Generally long slopes but I take it out of 5th gear and put it in 4th. It does not work well in 5th. I am up and down hills all the time in town so I just leave it in 4th unless I am on the highway. If you are going down a grade, lightly tap the brakes but do not really apply them, you should feel a slight shift of the torque converter loccking up, if this slows you down to much lightly touch the gas pedal and you will feel the converter unlock and you will gain speed. As far as the comment from Jerrydog about durability I do not think Toyota would put in this feature if it was going to cause damage. The torque converter lock and unlocks all day long even in normall driving. Mine is 8 years old mostly all in the mountains and has never had a problem. Around here you follow people going down long grades for a mile or so lightly riding the brakes the whole time to maintain speed. That seems much more damaging to me.

Sure it will damage your brakes overtime, but how much are brakes compared to a tranny or engine rebuild? Its like people who slip the clutch on a hill, sure you can do it but your wearing out your clutch faster...

 

[03_4x4Runner]

Sure it will damage your brakes overtime, but how much are brakes compared to a tranny or engine rebuild? Its like people who slip the clutch on a hill, sure you can do it but your wearing out your clutch faster...

Do whatever you want. Have you ever went down Pikes Peak in Colorado? It is a very steep and long downhill. They make you stop half way down and a ranger checks your brake temp. If it is over a certain temp they make you pull over and will not let you continue on untill the brakes cool down. There is usually someone waiting there with overheated brakes.I went the whole way down in like 2nd and 3rd gear and rarely used the brakes except on steep curves. I drive in the mountains a lot and always downshift even at highway speeds to maintain speed without braking. I am also on my original brakes after 8 years and 60k miles. Off road I do the same thing, constantly letting the engine brake going down steep grades. This also keeps the tires from slipping on loose terrain downhill and makes it easier to control.

 

[Jerrydog]

Do whatever you want. Have you ever went down Pikes Peak in Colorado? It is a very steep and long downhill. They make you stop half way down and a ranger checks your brake temp. If it is over a certain temp they make you pull over and will not let you continue on untill the brakes cool down. There is usually someone waiting there with overheated brakes.I went the whole way down in like 2nd and 3rd gear and rarely used the brakes except on steep curves. I drive in the mountains a lot and always downshift even at highway speeds to maintain speed without braking. I am also on my original brakes after 8 years and 60k miles. Off road I do the same thing, constantly letting the engine brake going down steep grades. This also keeps the tires from slipping on loose terrain downhill and makes it easier to control.

I've been over the rockies a few times and up thru the passes outside of Denver up into Winterpark and Grandby....but like I said in my original post this is not everyday driving the average person does so why put wear and tear on a drivetrain by having this happen automatically when your taking the kids to a soccer game saturday morning approaching a stop ight level ground 68 degrees and sunny? Besides isnt that what the down hill decent button is for, extreme conditions like mountain driving? Why the redundency? Makes no sense to me and also wasted gas. Also you seem very concerned with saving wear and tear on your $200 brakes when you might want to be concerned with saving wear and tear on your $4000 engine and $3000 tranny....Just my .02

 

[MICA4R]

Do whatever you want. Have you ever went down Pikes Peak in Colorado? It is a very steep and long downhill. They make you stop half way down and a ranger checks your brake temp. If it is over a certain temp they make you pull over and will not let you continue on untill the brakes cool down. There is usually someone waiting there with overheated brakes.I went the whole way down in like 2nd and 3rd gear and rarely used the brakes except on steep curves. I drive in the mountains a lot and always downshift even at highway speeds to maintain speed without braking. I am also on my original brakes after 8 years and 60k miles. Off road I do the same thing, constantly letting the engine brake going down steep grades. This also keeps the tires from slipping on loose terrain downhill and makes it easier to control.

You have a v8, that engine is a cast iron beast! So i don't blame you for down shifting. However with the v6 and the (aluminium and high temp plastic engine) i treat it gingerly.

The only solace i have is that you and i have the same trans. Thus its unlikely that a v8 trans is going to be destroyed by a v6.

Pikes peak is a lot of fun. Esp in snow.

 

[chromefinder]

I have a new 2011 SR5 V6 4x4 w/ auto trans that does this consistently with the shifter in D mode. I don't like it one bit. My dealer service depart claims to to have no knowledge of this and says they can't reproduce it.

 

[MICA4R]

Engaging/Dis-Engaging trans while rolling any thoughts?

Is it bad for the transmission to drop into Neutral when coming to a rolling stop to prevent engine braking?

And is it bad to drop it into D when traveling at say 30 MPH when the light turns green? (rearely ever do I do this but just want to be sure)

I am still trying to get used to Automatic transmission. I just want to be sure that I'm not decreasing the life of the trans.

 

[snowbrdr033]

I used to do that when decelerating to stop lights or stop signs in my old (3rd gen) 4R. I never noticed any negative effects as a result of doing it, but I was told that it can, over time, have an adverse affect on the tranny.
(that person, or I could be wrong, but I'm simply stating what I've heard).

Personally, I would think that if you only did it once in a while and not 10x/day, then you would be fine. Again, I could be wrong.....any further input is appreciated! I'm actually interested in this topic too.