Toyota Previa (1990 - 2000) - 2.4 petrol Auto transmission problem

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Tue 7 Mar 2006 20:11
2.4 petrol Auto transmission problem - R.Turpin
2.4 petrol 1994. Done 160,000 miles without breakdown. New fault as follows. The car has 3 forward gears plus overdrive. There is also a "lock up" mode which engages at 50-60 mph depending on how hard the throttle is pressed.
This now makes a nasty grinding noise when it engages. Once engaged the car works fine as long as at least a little throttle is kept open. If you lift off, it seems to re-engage when you accelarate again.
I'm guessing, but I think it's part of the torque converter?
The problem is that the car is not worth spending much money on plus we are going skiing in it on March 25th.
Does anyone
a) Know how it works, and will it disintergrate on the motorway etc???
B) Know any way of fooling the lock up so that it simply never engages. (Being dependant on speed AND pedal pressure, I presume it is governed by centifugal force AND vacuum.)

Hope there is an auto expert amongst the backroomers!

Regards Richard.

Edited by Pugugly {P} on 12/01/2008 at 17:24

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Tue 7 Mar 2006 21:39
Previa Auto transmission problem - Aprilia
I don't have direct experience of this 'box (Aisan-Warner A46DE) - but I have worked on the very similar A43DE as fitted to the Celica.

There is no vacuum control on these 'boxes. There are three solenoids controlled from an ECU. The lock-up clutch is situated in the torque convertor and is controlled by activation of the No.3 solenoid. Disconnecting the feed to No.3 solenoid will disable lock-up. The ECU may detect this though, and flash the mode light at you as a fault warning. There should be no other ill-effects.
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Wed 8 Mar 2006 00:02
Previa Auto transmission problem - R.Turpin
Aprilia (Lancia or just Roman?)
Thanks for the info. Sounds very promising. Next Q is how/where do I find the feed to the No 3 solenoid? If you don't have experience of this particular box, where would it most likely be? Underneath?
Richard.
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