Transmission S shift issue?

[Ripper238]

The car isn’t going to let you do something that won’t work. You’re driving a 4.5k lb brick at 80mph up a hill. It’s physically not possible to maintain that in 5th gear. Have you ever tried riding a bike in the highest gear up an incline? It’s like that.

Absolutely. But let me give a more specific example.

I'm in cruse control at 78mp and 3/4 up the hill it drops to 4th, i crest the hill and start going down and its still in 4th, i disengage cruse control and its still in 4th as it decelerates. I manually go into S mode and try shifting to 5th and nothing (im now at ~70mph). So i put it back in D and pump the gas and it goes into 5th.

This seems to only happen with this exact scenario.

 

[TEujunga]

Absolutely. But let me give a more specific example.

I'm in cruse control at 78mp and 3/4 up the hill it drops to 4th, i crest the hill and start going down and its still in 4th, i disengage cruse control and its still in 4th as it decelerates. I manually go into S mode and try shifting to 5th and nothing (im now at ~70mph). So i put it back in D and pump the gas and it goes into 5th.

This seems to only happen with this exact scenario.

Totally normal. All part of Toyota's "grade logic" programming for the trans. In this particular case (cresting a hill), the trans will hang onto 4th for way longer than necessary because it "thinks" the uphill grade might resume, requiring another downshift into 4th. The programming would rather stay in 4th too long and be absolutely sure you're done climbing hills than shift into 5th too early and start having to "hunt" between 4th and 5th. And yes, trying to "tell" it to shift into 5th using S mode will have no effect in this scenario.

 

[ElectroBoy]

Totally normal. All part of Toyota's "grade logic" programming for the trans. In this particular case (cresting a hill), the trans will hang onto 4th for way longer than necessary because it "thinks" the uphill grade might resume, requiring another downshift into 4th. The programming would rather stay in 4th too long and be absolutely sure you're done climbing hills than shift into 5th too early and start having to "hunt" between 4th and 5th. And yes, trying to "tell" it to shift into 5th using S mode will have no effect in this scenario.

I run into this annoying uphill scenario when driving *without* cruise control. As I crest the hill in 4th and the road levels out, or even starts to decline, the transmission stays in 4th for quite a while, even if I back off on the pedal to lighten the load. After what seems like a long time, maybe 5-10 seconds, it finally shifts. My 3rd gen did not behave this way. After the transmission downshifted during a hill climb or accelerating to pass a car, when I’d lighten up on the pedal the transmission would rather quickly up shift.

Damn “grade logic”.

 

[BobsTrail]

I feel like it also changes shift points. The lower the number, the higher the revs before it shifts. Anybody else feel this?

In my 2013 I always put it in S5 upon startup, this reduces the lag when wanting a downshift on a freeway ramp and does appear to slightly help the shift points.

When off-road I always use S mode to limit it to S2 or S3. Sometimes S4 when in 4L and on sand.

 

[CavPro]

The manual does talk about this issue, but not in great detail. It has sections on S mode and AI-Shift mode.

"The engine speed may remain high after releasing the accelerator pedal. This does not indicate a malfunction".

 

[MaddoxPics]

Really only use the S mode for when I want to rev out higher. Whether that be when going up a steep incline on the trail, mud/snow, or when there's a short onramp.

 

[Ripper238]

Totally normal. All part of Toyota's "grade logic" programming for the trans. In this particular case (cresting a hill), the trans will hang onto 4th for way longer than necessary because it "thinks" the uphill grade might resume, requiring another downshift into 4th. The programming would rather stay in 4th too long and be absolutely sure you're done climbing hills than shift into 5th too early and start having to "hunt" between 4th and 5th. And yes, trying to "tell" it to shift into 5th using S mode will have no effect in this scenario.

Really great info. Thanks for confirming this is normal. I'm so paranoid about my transmissions in my vehicles because I've blown so many over the years.

I guess the next question is when is the best mileage to change the transmission fluid? Lol

Sent from my SM-N960U using Tapatalk

 

[MaddoxPics]

I guess the next question is when is the best mileage to change the transmission fluid? Lol

Changed mine at 55. Supposedly it's a "lifetime fluid" unless you do a lot of towing, but mine was already dirty. Then again I do have some added weight with the bumper, winch, rock sliders, as well as have bigger tires. All of which will cause more work for the transmission.

I just did a fluid exchange though, not the full hardcore dropping the pan and what not.