[Ulster_Man_OZ]

My Avalon started giving me some grief few months ago when It would Jam itself in 4th gear. I was still able to use the overdrive to drop it down to 3rd, then 2nd and Low ratio for taking off at the lights.
I decided to drop out the transmission valve body and replace the shift solenoids, replaced the gaskets
My car now drives well, very smooth through the gears but still continues to lock itself in 4th gear. It does it very intermittenly and more so when its hot. It will still drop down the gears if it switch off overdrive down to 2nd and low.
What i have noticed when it does lock itself in 4th, i put the shifter into neutral and the engine keeps revving and wont drop.. around 2000rpm, if i switch off overdrive the revs will drop.

Could it be the engine ECU? it does not show faults with engine management indicator.. the light works when ignition is switched on
Could it be the throttle position sensor?
Could it be transmission speed sensor?

Could someone point me in the right direction?

Motor has done 210,000km,

Cheers in advance

 

[sdspeed]

Any codes from any source?

 

[Bigplanz]

If you enter the transmission model number in google, you will find a PDF of the factory workshop manual for this transmission.

 

[Ulster_Man_OZ]

As I mentioned, there is no engine management light on. I dont have anything to plug in and get any codes if there are any

 

[Ulster_Man_OZ]

I had it on a long drive yesterday and using cruise control, it started to cut in and out very erratically.
when I put the auto sifter into neutral, the revs stayed at 2000rpm, I gave it a quick rev to 4000, the revs dropped to 1000 but gradually increased again to 2000.
Very weird.

 

[Kingdom934]

I've never heard of this happening. These Avalon (at least in the USA) are throttle body cable driven, so no drive by wire.

If it locks itself in 4th, if you slow down to a stop, does it still stay in 4th so you'll have a hard time to get going from a stop? Or does it downshift when coming to a stop, it's just that it won't downshift if you need to speed up (i.e. passing)?

 

[Ulster_Man_OZ]

I've never heard of this happening. These Avalon (at least in the USA) are throttle body cable driven, so no drive by wire.

If it locks itself in 4th, if you slow down to a stop, does it still stay in 4th so you'll have a hard time to get going from a stop? Or does it downshift when coming to a stop, it's just that it won't downshift if you need to speed up (i.e. passing)?

Yes its cable driven throttle and has cruise control.
If I slow down to a stop, it will drive off in low gear but quickly changes to 4th. I've burnt the oil and changed it twice already. Therefore when it starts doing it I use the manual shifter to save me changing the oil.
I took it to a transmission repair shop and he plugged in his computer and no fault codes were showing.