DaveyUK

Okay so I've got a early facelift SC430 6 speed with 79k miles on it. I've recently had the ATF changed (well as much as you can by dropping the pan) to try to ease a poor shifting problem but the problem is still there.

The shifting is NOT smooth, particularly downshifting when slowing down where it often drops into a too low gear and my revs hit about 3000! Very unrefined. I also have been having some neutral dropout, mainly after some moderately hard braking, but by no means hard, emergency braking.

After some research it does sound like this problem:

https://www.clublexus.com/forums/ls-3rd-gen-2001-2006/915415-lexus-transmission-down-shifting-hard-help.html

Interestingly the problem seems to go away when I put the car in 'Power' mode?

So is it likely to be ECU related? There seems to be zero discussion this side of the Atlantic of this problem and if you know anywhere in the UK that could fix my ECU I'd appreciate it!

lexixel

1. Clean MAF / temp sensor
If symptom still persists
2. Check ATF level (add)

Lavrishevo

iTrader: (1)

I have experienced some hard downshifting when the transmission was under-filled. But with your description about changing modes and it affecting it that drastically I think ECU might be a good guess. They will start to go bad with age.

Bgw70

give this a try…it’s free…from our longtime CL friend Harold57…
I did it many times in my 2002…and it worked. I had different symptoms.

If you want to reset the ECU without losing your seat and stereo settings, perform the following procedure:

1. Get in your car and insert key. (It doesn't matter if you close the door or not.)

2. Turn the key to the on (not start) position.

3. Press the gas pedal to the floor.

4. Hold the pedal to the floor for five seconds, then turn the key back to the "off" position (don't remove the key), then release the gas pedal.

5. Wait 2 minutes.

6. Remove key.

7. Done

Yes it works. Done it many times. Works on all years, 2002-2009.

DshngDaryl

See if you can eyeball your transmission mount. Check to make sure there is not a crack in it