A340E / 30-40LE gearbox oil change?

This gearbox seems to be in many many Toyotas all over the place which is good, so there's lots of videos of how it's made and works etc. It's a 3speed + overdrive unit with IIRC 4 solenoids.

It's fully controlled by electronics, which I think are buried under the gear shifter to the passenger seat side: The gearbox ECU and relays are all here. There's a way to test the solenoids from the cable that comes out the side, mine seems to work fine but I haven't driven it much yet so it would be nice to click though all 4 solenoids at some stage in the garage just to check - for instance I've not gone fast/far enough to use the torque converter lockup (if fitted?!), so I'm still looking to find how to do that. They seem to be the main potential failure in that box.

So the post is for advice about oil as I seem to have failed to learn much about that. I think it needs Dexron III or 6, is that right?

Dexron III can be had quite cheaply:
http://www.ebay.co.uk/itm/ATF-Dexron-III-Automatic-Transmission-Fluid-DIII-5-Litres-Made-in-UK/121625415146

The slightly better IIIH here:
http://www.ebay.co.uk/itm/Fully-Synthetic-ATF-Dexron-IIIH-Transmission-Fluid-5-Litres-Made-in-UK-/111716509174?

Edited:
Note1: Dexron 6 or VI appears to have some controversy about seal compatibility with Dexron III, not necessarily on Toyota/Alsin boxes but I'll not risk it.
Note2: Type T-IV ATF is not suitable for the A340 boxes.

I plan to do a simple oil-pan-plug change and then repeat at a later date; rather than a whole flush. The filter is a sieve IIRC - so it should be fine if the sump plug is fine.

I'll measure what comes out and put that much back in, is it a fill via the dipstick hole?
I've heard overfilling is very bad for them.
To check the level it's a warm running gearbox - yes? Is there a way to check it cold?

A bit more info as I've trawled the web:

http://www.toyota-supra.info/forums/mkiii-faq/1043-auto-trans-oil-change-made-easy.html

Basically you should NEVER flush the fluid in an autobox unless it's new.
Ours are not new so they should never be flushed.

The reason is that a flush releases too much dirt in one go; which clogs up the oilways, valves etc.
The way to clean dirty fluid is to do a drain and fill on the gearbox sump only (about 40% of the total oil) on a regular basis which will gradually and safely clean the whole box.

I'm not sure if dropping the pan is worth it on a metal mesh filtered box, I'll pop my USB endoscope in to have a quick look at how clean the floor of the pan is and only take it off if it's dirty or a solenoid needs replacing. Dropping it will need a new gasket etc and it's quite messy.

BTW I also found what the codes for the gearbox means:

30-40LE
 L = Lockup (Locks up the torque converter if conditions permit)
 E = Electronic. Basically the manual level selects possibilities and the solenoids select the gear.

the gearbox is a 3 speed auto to which they've added an overdrive (another planetary gear + clutch) and lockup.

2 Solenoids select gears 1 2 3 4
1 Solenoid for the lockup
1 Solenoid for the overdrive

This seems to be one of the best discussions on it:
http://www.pirate4x4.com/forum/toyota-truck-4runner/587521-a340-transmission-issues-faqs.html#/topics/587521?page=1&_k=7dlrrc

You can see the internals (minus valve body) here:


The 3 pots in the top-right corner are to make the changes smooth, the piston + band top centre is an actuator + brake band, the pistons for the clutch packs are concentric to the shaft and very short, fat things you can just make out on the cutaway in the 'how it works' link.

And here's how it works, I think it's actually the A340 box he's got cut away there.

https://www.youtube.com/watch?v=HcNH9AFWaNI

Oh, and if a gearbox has a lockup and the lockup fails, it can overheat because the lockup reduces the heat output quite a bit - so a persistent overheat could be down to that. (See https://hiace-super-custom.forumotion.com/t3030p75-worth-keeping-my-hiace#16222)

Toyota/A340E Wiring diagram (from Supra forum)
http://www.turboninjas.com/mk3supra/tewd/Flyout-2.jpg

Ok, progress!

I checked the fluid colour on a nice white tissue and it was a definite brown, not the nice pink/red of new stuff so I'm glad I looked. I'd recommend any owner of any auto transmission to check because if you leave brown stuff in for too long it won't do your van any good. It disturbs the changes too: once clean it should change like new.

So I plan to get 10L for 3 partial changes, draining the pan and refilling with an equal amount.
The first can be done straight away, the next will have to be spaced by a few hundred miles to let it do it's work.

Going with fully synthetic Dexron IIIH as it cleans and is good stuff. From what I've read the transmission runs cooler with it too: which means less wear and less fuel.

Bidding on some of this now: http://www.ebay.co.uk/itm/111716509174

Changed out 3.6 litres of quite brown fluid for some super new red DIIIH fluid today, so we shall see next time I move it.

To get it out I used a plastic measuring jug and my finger, quite a good way but helped by having the van about 2-3' off the ground.. I did jack the front up a bit too as the drain is at the back of the box.

Quite 'interesting' getting the new fluid in as it all goes in via the A/T dipstick tube. Luckily I had a length of fuel hose and a funnel that could plug into it, then I used the same (cleaned) pot to tip the same amount of new stuff back in again with a spill tray under it for drips.

I'll probably give it a few hundred miles to work and clean until I change it again, apparently rushing or flushing can dislodge too much dirt at once - which can lead to very bad things, like needing a new box.

Good write down.