auto transmission not shifting or shifting intermittently

[brett12345 Lurker Find all posts View Profile Close brett12345]

Hi,
I have a 1996 90 series automatic Prado 3.0D with 250,000km that has started recently not changing up a gear. It will get stuck in second or third and never shift up. It happens randomly, both when the car is cold or warm, but more often when I am just starting out. Shifting into park, neutral, or reverse does not help. It will still downshift fine. Usually after a few km of driving it will then start shifting normally. I have tried with the OD on and off and also the PWR ECT button on and off and doesn't seem to make a difference.

The transmission oil was flushed about 10k km ago, and looks clean on the dipstick and at the correct level.

Would this be a solenoid issue? Is there a way to check the solenoids?

Thanks for any advice.
Brett

[dkosulla Lurker Find all posts View Profile Close dkosulla]

Heya mate,

no idea if still a problem for you but had similar in my 02 petrol that was doing my head in!!

Managed to pull code and resulted in faulty TPS. Easy fix swapped over and touch wood so far has been back to normal with gear changes.

Hope this helps someone.

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

Hello, I'm wondering if the OP has resolved his issue?

my 1997 90 2.7 with 150,000km was doing something similar, it was fine forever, now in D it stays in first off the line until about 3,000 rpm unless I play with the accelerator, then when coasting under 25 kmph will down shift to first. Shift to 2, and seems like L, will never shift out of first.

I have used the below techniques to reset my TPS, and off the bat they worked at least in D but then wore off after the next restart. But my mechanic is trying to tell me that he doesn't think (hasn't been underneath yet) that the transmission on this model is not controlled by the TPS.

Any help would be appreciated... as my mechanic is showing up tomorrow.

Thanks

TPS Reset: https://www.caraspect.com/throttle-p...-sensor-reset/

[SamSta Member Find all posts View Profile Close SamSta]

Pretty sure the auto trans is controlled by the ECU. The TPS is heavily involved in the functioning of the car so it's quite possible it's to blame. I somehow doubt it will be the ECU. I've never heard of shifting problems with this trans. They're known to be fairly bulletproof (mechanically at least).

When you say the TPS reset worked, then started playing up again, that's a fairly good indication something to do with the TPS is the problem. I've heard of the butterfly in the valve body becoming sticky due to the soot build up from the EGR. Take your top mount intercooler/ crossover pipe off and have a look down in the throttle body to assess the condition. If it's really mucky down there, expect to remove the intake manifold and EGR pipes to give them so good clean. I would personally block off and remove the EGR after this and put it all back together.

Hope this gets you on the right track

[Turdo Biesel Lurker Find all posts View Profile Close Turdo Biesel]

The ECU capacitors commonly leak an acid like substance into the circuit board and it corrodes the 0.5mm wide copper tracks that control the auto trans. Very common on supras, surfs, hiaces, and Prado’s. I have repaired 6 or so each year, with a magnifying glass and a superb steady hand that would make a neurosurgeon jealous. The Prado ecu is horizontal above the glove box and is less prone to issues than the Surf.
very easy to identify the broken or corroded tracks once you take it out and use a small torch to inspect. Also if you have access to a friends ecu you can swap that in and see if it works.
goolge ‘leaking ecu capacitors’

[SamSta Member Find all posts View Profile Close SamSta]

The ECU capacitors commonly leak an acid like substance into the circuit board and it corrodes the 0.5mm wide copper tracks that control the auto trans. Very common on supras, surfs, hiaces, and Prado’s. I have repaired 6 or so each year, with a magnifying glass and a superb steady hand that would make a neurosurgeon jealous. The Prado ecu is horizontal above the glove box and is less prone to issues than the Surf.
very easy to identify the broken or corroded tracks once you take it out and use a small torch to inspect. Also if you have access to a friends ecu you can swap that in and see if it works.
goolge ‘leaking ecu capacitors’

Ahh that's interesting and good to know! Thanks for the knowledge. I've successfully done trace repairs on a USB B port, like you with a magnifying glass but not so careful hand, made a dog's breakfast out of it but it worked in the end. Is the job somewhat comparable or even trickier again? Thankfully I don't have the issue now but as an avid DIY repairer/tweaker, it's good to know these things.