Now I'm confused.... If it's 100% throttle opening before the switch, what the heck is this switch doing?

 

It's doing what it's named for: kicks down the transmission to a lower gear. In my test, at 60mph it's the difference between dropping to 4th or 3rd gear.

It's actually an old tech feature. End result is that the car goes really fast, or it believes you really meant it and engages ludicrous speed.

 

What OBD2 scanner are you using? I connected my KIWI4 using OBD Fusion app and here's what I got. This is just with the IGN in the ON position, engine off (not sure if it makes a difference)
I don't think the throttle plate is moving with the engine off, but I'm not getting 100% pedal output.

pedal on the first stop:



Pedal all the way down.

 

I have an OBDlink LX dongle and am using the OBDLink app. Paid the $10 for Lexus specific diags, so it connects to more networks than just the generic OBD2 protocol. I just set it up to monitor the PIDs related to throttle and accelerator position. Was pleasantly surprised it had the kick down switch flag as an available parameter.

 

Did a quick data capture and created this chart from it showing accelerator position, throttle plate position, and kickdown switch position. From all indications, there's no difference in throttle position when you hit the kickdown switch. I did this on two separate trials, and the results are interesting to say the least.

 

Yea Lexus has been employing this for a while, had it on the SC400. Engages hard downshifting, no impact on throttle opening. Think it's mentioned in the manual

 

Updated post with chart from data log. See previous post.

 

Thanks for posting the data. Very interesting.

 

Thanks all for the technical info. Now, if I may ask a non-technical question where I hope to understand the answer.

If one shortens the springs as has been illustrated, does the transmission shift to a lower gear at the same pedal location as compared to stock length springs?

Thanks

 

Cutting those springs only affects the *effort* needed to push the kickdown button. The general complaint is that it feels like you've floored the pedal and engaging that button requires extra effort. The spring mod makes it a bit easier to floor it and hit the kickdown button at the same time.

 

Exactly correct.

I just realized I forgot to mention, I was in Sport mode (not Sport+) and TVD in slalom (my standard every time I get in the car mode). I am thinking I need to replicate this with my IS F as it is on the original '08 engine management software - I have refused the "upgrade" to let the brake override the throttle every time I have been to Lexus, and I always will. I could flash it myself with my Techstream subscription, but I don't want to invoke this feature if I can avoid it.

 

Got it, thanks

 

Yep, me too. I never applied the; change to my ISF, but I now have the "feature" on my LC and I absolutely HATE it

Lou

 

Sort of replying to a dead thread, but in the graph by lobux in the #35, is the purple line showing full throttle (I mean 100% throttle, not the position of the gas pedal)? Or is it like 80% throttle or something

 

There is no indication at 100% ever for the accelerator position or the throttle position. That's consistent across all Toyota engine management.