Downshift when approaching stops

Trac1

New member
May 19, 2024
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Is it normal for the car to downshift so much when approaching stop signs, intersections, or going downhill? It isn’t abrupt it just seems like the car won’t coast or freewheel at all. I have the proactive driver assistance off which really accentuated that feeling of slowing down. I need to stay on the accelerator lightly until I am close to stopping. Any suggestions?
 
I noticed my week old GX would aggressively downshift coming to a stop. But after 1500 miles its adapted some and isnt as abrupt. If it doesnt smooth out I plan on bringing it back to my local dealer to have them reset the transmission to re-learn the adaptations to see if it is smoother.
 
Wondering if this is partly due to the “small” 6 cylinder and 10 speed trans…. Car wants to be ready for whatever comes next (proactively in power band incase you need to go).
 
just unplug the negative terminal on the battery for 30 min. It resets the Transmission ECU. I didn't lose any dash/radio settings when I did this either.

It makes a noticeable difference
 
I received my GX 550 about 4-5 weeks ago. I have not seen/heard/felt my transmission downshift in any manner I could call an issue. Mine must have been programmed differently. I appreciate how folks are putting their issues on the forum - Thanks.
 
My OT+ (1800 miles) has been doing this since day 1. The sensation is similar to gently riding/tapping the brakes on a downhill, not jarring, but certainly noticeable. I have somewhat adapted to the feeling, but it is annoying.
 
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There is a setting somewhere in the menus that you can turn the downshift assist on or off. Yes it is a little aggressive when it is on but I would imagine it would come in handy if you tow.
 
My dealer reset the transmission computer and it seems to have gone away. The catch is that he said they all do this eventually and that this is only a temporary fix. If mine comes back, I’ll try the battery disconnect idea before going back to the dealer.
 
Have you all tried changing the trailer brake controller settings? I noticed when I got my car that one of the Trailer brake types was on by default. I turned it to “TBC off” since I don’t regularly pull a trailer (and certainly not one with brakes). Just curious if these settings might also impact the way the car downshifts.? Just a theory. FWIW I haven’t noticed any unusual downshifts, but also only have 2200 miles. This is under Settings -> Vehicle Customize -> Utility -> Brake Type
 
There is a setting somewhere in the menus that you can turn the downshift assist on or off. Yes it is a little aggressive when it is on but I would imagine it would come in handy if you tow.
Do you have any more info on this? I haven't seen anything like this in all the menus and sub-menus.
 
The automatic downshifts are way too aggressive, in my opinion. You'd think at least in Eco mode the vehicle designers and programmers would let the truck coast along in a high gear instead of aggressively downshifting. I'd love to see Lexus or the aftermarket offer a re-mapped Eco mode where you could coast along in 10th gear in Eco mode instead of the damn thing constantly engine/transmission braking as you coast and your speed naturally decreases due to all the friction variables.
 
Have you all tried changing the trailer brake controller settings? I noticed when I got my car that one of the Trailer brake types was on by default. I turned it to “TBC off” since I don’t regularly pull a trailer (and certainly not one with brakes). Just curious if these settings might also impact the way the car downshifts.? Just a theory. FWIW I haven’t noticed any unusual downshifts, but also only have 2200 miles. This is under Settings -> Vehicle Customize -> Utility -> Brake Type
Mine was set to 0-4999 (1st setting) from factory. No difference in braking with it set to TBC Off that I could discern
 
Funny, I actually like the way the transmission tries to hold your driving speed with a couple of downshifts to give it a bit of compression breaking, maintain speed and not make you ride the brakes as much. On a steep decline the truck will eventually overcome the slight compression breaking and then almost speed up as the rev's kick in. This may have something to do with the turbos spooling up. I think it is nice and hope they don't "fix" this. I find it quite annoying when you don't get some engine breaking.
 
Funny, I actually like the way the transmission tries to hold your driving speed with a couple of downshifts to give it a bit of compression breaking, maintain speed and not make you ride the brakes as much. On a steep decline the truck will eventually overcome the slight compression breaking and then almost speed up as the rev's kick in. This may have something to do with the turbos spooling up. I think it is nice and hope they don't "fix" this. I find it quite annoying when you don't get some engine breaking.
I agree, but I think ECO mode should let you coast free. If you knowingly choose Eco mode then you know what you’re getting into!
 

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