teo4runner

Hi,

I would like to make my own fully programmable ecu to control the transmission, so I need to know much more info about the trans operation that there is in the workshop manual...

OK, so there are 2 solenoid valves to select the gear(1-4), one for low range transfer, and one for the converter lock-up

The first 2 for the gears, and the one for "low range gears" are no mystery for me and their engagement based to truck speed and tps(automatic) or with a + - switch("manual"), or even with the stock selector(D, 2, L) are easy for me to program on a "new" ecu. Or am I missing something?

The lock-up solenoid is not so clear for me at the time.... I suppose that for this one to engage the transmission side of the converter and the engine side must rotate at the same rpm... the transmission side rpm is calculated by the speed sensor on the transmission, and the current gear activated. The engine side rpm is measured by one of the pickup coil(which one?) inside the distributor(3VZE).... Or am I missing something?

As far as i found the lock-up is only activated in 3. and 4. gear.. Is this correct?


is the P, R, N "gears" selected mechanically by the lever? The same question for the rear wheel drive - all wheel drive?

Thanks for your time,
Teo

scope103

Which "workshop" manual were you looking at?
http://personal.utulsa.edu/~nathan-b...42operatio.pdf

Don't forget that you will also need to monitor two speed sensors (before/after transfer case), the temperature sensor, brake, O/D switch, and cruise control. You will need to monitor the TPS whether or not you're "automatic," as it affects lockup.

The stock ECU does not monitor engine speed, so I don't believe it attempts to synchronize the transmission before lockup. It may, however, apply some intelligence to minimize the speed difference before engaging lockup. According to this page lockup can occur in 2d, 3d or OD, but generally so briefly you only see it in OD.

Good luck, and let us know how it turns out.

teo4runner

I am going to monitor all the existing sensors, and even add same if needed...

The main goal is to manually change the gears with a + - switch, and use another switch to turn on and off the lockup manually, but it will engage only when the engine and trans are synchronized, it will stay locked until there is a gear change or if I turn it off manually, or if the engine rpm drops too low..

After that I test it manually I will program the fully automatic "mode"....


I am still looking for the answer for this question...
"is the P, R, N "gears" selected mechanically by the lever? The same question for the rear wheel drive - all wheel drive?"

rustypigeon

P,R and N are completely mechanical. Forward gears are selected by soleniod positions when the shifter is in D.

The A340F 4wd selection is also completely mechanical, with no electronic control.

teo4runner

Sorry I have written the wrong title.. It is A340H, not F

I believe that it doesnt change the answers that I received so far....?


What is the difference between the D, 2, L positions? I see that in the FSM operation table different clutches and brakes are activated for the same gear but in different lever positions....
D - 1.gear - C0, C1, F0, F2
2 - 1.gear - C0, C1, F0, F2
L - 1.gear - C0, C1, B3, F0, F2

D - 2.gear - C0, C1, B2, F0, F1
2 - 2.gear - C0, C1, B1, B2, F0, F1
L - 2.gear - C0, C1, B1, B2, F0, F1

So what is the difference between the 1st gear in the D,2 position and the 1st gear in the L position? The same question goes for the 2nd gear, and 3rd?

If I want to use all 4 gears I need to be in the D position, not the 2 or L?


What would happen if I would leave the transfer lever to the H2 position, and activate the no.4 solenoid? Would I have low gears on only rwd? Or would I break something...

scope103

I'm no transmission expert, but I believe the difference for 1st gear in D v. L has to do with whether the truck coasts, or drives the engine (engine braking). Note that the mechanical difference is only whether B3 is activated, which controls whether the rear planetary carrier can turn clockwise.

Whether you can "use" all four gears in 2 or L depends on whether the various clutches are mechanically limited (by the shift position) or electrically limited (the ECU senses the shift position and doesn't activate various solenoid positions). I don't know the answer.

As I read the manual, the front drive shaft is in neutral until C4 is activated. The solenoid appears to only work C3 and B4. So activating the solenoid with the transfer lever in H2 would probably give you rwd low, with the front shaft still in neutral. Whether that would break anything, I can't tell.

Good luck!

Mandy Tuning

you cant have all 4 gears in 2 or L cause the valve body will limit it. the transfer case low speed acitivates by solenoid and the front driveshaft activate by valve body and correct shift position.you can go 4wd hi up to 35mph but not more than 5 mph on 4low. will be nice to use tach signal so you can adjust the shift points by rpm not only
by speed

rustypigeon

Ouch! Don't do that! In H2 and H4 the sun gear and carrier are locked together providing direct drive. When you shift into L4 the ring gear is held and the sun drives the carrier providing gear reduction.

If you had the selector at H2 and activate no4 solenoid, you now have the sun gear locked to the carrier (because of H2 selection) and the ring gear held to the transmission case (because of no.4 solenoid activation). The carrier is basically trying to move the ring gear which is locked in position. In simple terms, you just locked the transmission output shaft to the transmission case, something is going to break.

ThatGuy1295

Reading this thread reminds me of the time I tried runing an A340F with my own wacky idea of paddle shifters on the steering wheel. This was a long time ago I swapped an auto from a 3.0 95 4runner into an 89 3.0 manual truck and tried running the trans off of selectable shifter dealio without the computer. Well this was before I knew better, soooo I destroyed the transmission. I wired the solinoids to switches thinking they were each just simply controlling one gear at a time. Not the case. It grenaded about 50 miles into it. I have no idea what I actually did but im sure it was what I did. Probably engaged 2 gears at once without knowing Was really just an experiment. But ya those are pretty complex transmissions.

Mandy Tuning

you will have a transbrake or maybe a "transbreak"

teo4runner

Thanks for the answers..

So here is what i learned so far...
- if I want to shift all 4 gears, I need to put the lever in D
- if I want to use rwd with low gears this is not the way to do it

Will I have engine braking if i am in D and I manually downshif from 4 to 3, 3 to 2, 2 to 1?

scope103

I don't believe there is a "4th" gear in the A340H, but there is O/D.

Assuming that when you say "manually downshift" you mean "electronically," I'm pretty sure the answer is "no." But the easy way to tell is take the truck out, get it up to 2d with the shifter in D, then take your foot off the gas. I expect it to coast. Now try it again with the shifter in 2. I expect you'll get engine braking. In that case, the shifter position (not the solenoids) is probably driving B3.

teo4runner

So this is how I can use the gears...?

D - 1,2,3,4 gears can be used of which 3. and 4. are engine braking
2 - 1,2,3 gears can be used of which 2. and 3. are engine braking
L - 1,2 gears can be used of which 1. and 2. are engine braking

And by using gears I mean that I can change it by using + and - electronically by activating the 1. and 2. solenoid combination...


What is the difference between 4th gear and O/D? Just the name?