Hi guys wonder if any of you can help me, ive got a 03 430sport with 52,000 on the clock and it has started to develop a gearbox problem .It started at the weekend and basically somtimes it won't change into top gear, you mainly notice it on the motorway and its not happining all the time just somtimes it does other times not.
Checked gearbox oil which is at the correct level hot and when cold and it looks pretty clean so dont think its that ,gear changes are smooth and repsonsive and today it has been fine, changed when it should under normal driving and after being pushed hard.
It has done it three times since thursday last week although i have been up to leicester and back in that time so ive done few miles . Each time it has done this i have stopped shifted through the gears put it back in to drive and it has then started to go into top gear .
Now i have always been led to believe that the lexus autos and V8s are bulliet proof so i am really concerned with whats going on.

Many thanks in advance for any help.

James

If you pull away in Drive all the time does it change up and down normally?

[quote name='dave1' post='690666' date='Sep 15 2009, 05:35 PM']If you pull away in Drive all the time does it change up and down normally?[/quote]
Hi m8 yes it does, changes up and down normally all the time through all the gears just not into top gear those few times on the motorway.

[quote name='jad' post='690687' date='Sep 15 2009, 07:21 PM'][quote name='dave1' post='690666' date='Sep 15 2009, 05:35 PM']If you pull away in Drive all the time does it change up and down normally?[/quote]
Hi m8 yes it does, changes up and down normally all the time through all the gears just not into top gear those few times on the motorway.
[/quote]

Might be worth calling into your local Lexus dealer and asking them if they have come across this before with other GS cars.
Might be worth going back to the dealer you got it from dependant on how long ago it was purchased.

I thought I had a problem with mine when I first got it - but there is a feature on these cars where it detects if you are going down a hill, and it will change down a gear to help keep your speed in check. This is not dependent on the cruise control, but works all the time. You can provoke it a bit by braking - watch the rev counter and you will see it jump up as it changes down, then if you press the throttle a bit it will change up again as it thinks you don't want it to assist in limiting your speed.

Assuming you're not actually going down a steep hill when it starts playing up, it could be something to do with the level sensor. I've no idea where it is, it could be in the gearbox, but there wouldn't really be any need for it to be tucked in there; since they are electronically controlled it could be anywhere really.

Just a thought!