Auto trans not finding the next gear.

[March Fly Lurker Find all posts View Profile Close March Fly]

I have a Prado 120 auto 4D4. Over the last 80,000km this problem has happened 4 times. For no reason at the start of the day the transmission won't find the next gear so the motor rev's up then the transmission will then lock in, causing a loud bang and a surge forward. This has happened at 10,000 and 50,000 intervals. It only happens for a short time and all the dash warning lights come on, when that happens I know the problem has gone for another 10,000km or so. I reset the dash lights by disconnecting the battery.

[Ammarg Junior Member Find all posts View Profile Close Ammarg]

Hows your auto oil looking? If its rooted not that it should he at 80K but if it is the valve body wont circulate the fluid at cold correctly.. just a thought

[March Fly Lurker Find all posts View Profile Close March Fly]

I should have mentioned that I've flushed and changed the oil twice, thinking that may help.

[Ammarg Junior Member Find all posts View Profile Close Ammarg]

Aha.. hmm thats different then.. im no auto specialist so id recommend taking that to a specialist getting them to have a look..might be something as simple as a valve spring has unseated or could be a rooted valve body.. did yiu use the correct oil?? And did u change the filter aswell?

[Rusty62 Advanced Member Find all posts View Profile Close Rusty62]

This has me stumped as well. Has happened on a couple of occasions as well, usually on cold running. Driving into a round-a-bout slowing to look and when clear accelerate and 'bang' into a gear. No lights or alarms then it goes away. I have changed my driving style to have a pause between lifting off brake to accelerator when cold.
Only started after i flushed the tranny with toyota WS oil. Hasn't happened in over 20000 km now so maybe a sticky solenoid in the auto. Have recently done a 3 lt part change (had 4 lt in the shed) but not seen the problem for a while.

What oil did you use for your flush? These boxes are fussy on the type of oil used.

Rusty.

To reset dash warning light you can use a scangauge or similar. Better than having to reset all the radio presets etc.

Are you running a power up chip?

[gxl_d4d Advanced Member Find all posts View Profile Close gxl_d4d]

Was the filter changed or removed and cleaned? Could be the filters blocked and the required oil flow is not being delivered.

[stanmiko Member Find all posts View Profile Close stanmiko]

There are a couple of ATF fluids around that will work OK in these trannies... I used the NULON Multi-ATF (Full Synthetic). My local Transmission Specialist uses Atlantic Oil Full Synthetic ATF and it is 1/3 the price of the Mr Toyoda stuff.

Sounds like a stuffed solenoid... or a piece of gunk that has one sticking.