Transmission Downshifting When Tapping Brakes Going Downhill
 

I noticed twice yesterday my transmission downshifting by itself going down hills when I tapped the brake. The first time it was 5th to 4th. Is that normal, it definitely felt unnatural.

2008 is250 awd ~84k miles

my car does it too and I understand it doesn't feel normal.
it really depends on what load the engine is experiencing for the trans to kick down a gear under braking, but it's entirely normal.

put the car in ECT PWR (press the button to the right of the steering column) and see if there is a change in downshifting.
for sure it will change the upshifting!

Good to know, thanks..
I could search but would leaving it PWR affect mpg? The car is already thirsty..

I believe its normal. Does it in ECT PWR too, i always leave mine on. I always thought it was the the car using engine braking to help slow down.

Completely normal.

My 11 IS350 does the same too so that's normal. Once you step on the gas, it'll shift up itself

At speeds over 60mph, on a declining grade, it takes a lot of throttle to get back to 6th. The hill in question is very repeatable. Placing in S mode reduces this a lot but sometimes it jumps down a gear or two just getting to S.

For the most part I get it into S while climbing the hill so that when I crest the hill I have it in a desirable gear and won't downshift from brake taps....

OP - yes, completely normal.
Try it!

from my experience going into S mode always results in 4.
this means if you're cruising at highway speeds above 60mph, going into S mode will downshift you into 4th!
if you're at city speeds under 40mph, going into S mode will still show 4, but will only shift up to that point until you manually shift up.

i noticed what you’re saying too. My 06 is350 downshifted to 4th and it holds It for about 0.5-1 mile some times before hitting 5th then 6th is this normal? Then sometimes it doesn’t. No matter if I let of the gas or tap it doesn’t change it. Only flooring it hard will. This is in hilly terrain only. On normal grades it’s perfect shifting.

Another thread on the same topic....
Brake tap induced downshift
https://www.clublexus.com/forums/is-...ue-or-not.html

Mine is very consistent >50mph if in 5th, stays in 5th. If in 6th, stays in 6th.
If <40mph, 99% of the time it limits at 4th. When below operating temp and crawling it may go to 1st or 4th.

Mods: if you stumble upon this, maybe merge this thread into the linked thread?