a340H 3rd gear shift problem

I have a 1985 Toyota 4runner with an A340H aisin automatic transmission that is experiencing the following problem with 3rd to OD shifting:

The transmission has a tendency to shift quickly into OD from 3rd and often seems to skip over 3rd entirely.

This occurs at all operating temperatures (i.e. even at cold start), whether or not the OD button is depressed.

In addition, when downshifting from OD to 3rd, the transmission will not stay in 3rd for more than just a second or two. Instead it will shift back to OD or downshift all the way to 2nd.

I did the mechanical shift test (with ECT disconnected) and the transmission behaves as it should (L=1st, 2=3rd, D=OD)

I tried swapping the ECT with one that I know to be good, but that made no difference, I also replaced the solenoids and filter, and adjusted the throttle cable linkage with no change in symptoms.

I'm now considering tearing into the transmission itself and was wondering if anyone has a guess as to what the problem might be?

Reply to
Mark
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The only other thing it sounds like, and the only thing you didn't mention was the valve body. I'm not sure if this can be cleaned, and it's a bit $$$ to replace, but it sounds like, other than this, the tranny is OK.

Google some Supra sites for more info on this. The Supra Non-Turbo had the same tranny and there's TONS of info about it out there.

One thing I am curious about: did you know this tranny was also used for Jeep Cherokees? I wonder how compatible they are (connector/bellshousing and prop shaft-wise...)

Since this is the case, there are THOUSANDS of them around!

Reply to
Hachiroku

Thanks for the advice. My FSM provides a pretty thourough discussion on removing and servicing the valve body without dropping the transmission so I'll try overhauling the valve body next. Thanks also for the Supra tip - I'll start searching through the Supra sites to see if I can find anything there.

I had heard that the A340H were used in the jeeps but don't know much about the compatibility either. It is good to know that there are a lot of them out there though...

Reply to
Mark

You have the FSM? Good! It looks pretty straightforward (my A340 hasn't shifted on it's own since I bought the car! I'm gonna have to replace the solenoids!) and looks like this can be done with the car up on ramps. Doesn't look like a LOT of fun, upside down with tranny sauce leaking all over, but basically drop the pan and have at! Something to look forward to once it STOPS SNOWING!!!

Where did you get the solenoids? Toyota, or an aftermarket?

I have to replace the speedo drive adapter too...$80 from Toy. I wonder if the Jeep thing is similar.

Reply to
Hachiroku

I got the aftermarket solenoids (mfg by Rostra) from bulkpart transmissions on the web (

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). The part number for the set I bought is 97420K.

Swapping them was a pretty easy job; the solenoids are immediately accessible and easily removed once you drop the AT pan. There is a wire harness under the valve body that connects to each solenoid. Just disconnect the wiring connection at each solenoid, then remove one retaining bolt per solenoid and they'll pop right out.

Reply to
Mark

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