Thanks a ton for that link - should be able to work on a design tomorrow, kinda busy at work today. Looks like there are 5 solenoids on the A340, S1, S2, SLU, SLT, and SLN (I'm looking at page 7, here.) I bet S1/S2 are just like the XJ AW4 S1/S2 but I'm not sure about the other 3. I also like the shift pattern on the A340 more from what I'm understanding of the chart on page 2, it looks like it has D/2/L. D works all gears, 2 will only allow 2nd or 1st (or 3rd, if you're already in it and downshift from D to 2, but once you drop to 2nd with shifter in 2 it won't upshift to 3 again), and L will only allow 1st (or 2nd, with same rules as 2, it will stay as high as 2nd until it downshifts, at which point it will stay in 1st.)
On page 8 there is a wiring diagram, it appears that solenoids 4 and 3 (SLN/SLU) are ground-side switched and fed by the fuel injector +12V supply, solenoid 5 (SLT) is switched on both sides by the ECU, and solenoids 1 and 2 are positive side switched.
Page 11 describes the solenoid functions. Solenoids 1 and 2 are gear selection and shift timing / firmness it appears, solenoid 3 is lockup clutch engage, solenoid 4 controls accumulator pressure, and solenoid 5 controls fluid line pressure.
Page 54 shows some debug info concerning solenoid duty cycle drive specs. It looks like fooling the Toy ECU into not setting a check engine light might be difficult, do you care about this?
Page 75 describes solenoid 4 operation.
Page 82 describes solenoid 1 and 2 operation.
s1 s2
on off 1st
on on 2nd
off on 3rd
off off OD
IIRC that is the same as the AW4. This makes sense since Rory from RADesigns makes shifters for both the A340 and AW4, and I think it's the same one.
Page 82 shows how the shift solenoids are wired. Looks like unlike the Jeep TCU, the factory Toy ECU uses a pull-up resistor (probably calculated to provide ideal max current to the solenoid) with a ground side switch transistor, and modulates duty cycle by changing the pulse width of the signal going to the driver transistor. When the solenoid should be OFF, the transistor is energized, and it is de-energized to turn the solenoid ON.
The number 3 and 4 solenoids appear to be set up the same way (page 86.)
The number 5 solenoid is driven from both ends. The schematic (page 92) shows a hybrid design for the driver, it's got the same current limiting / regulation resistor in the B+ feed, a resistor/back-EMF diode snubber across the solenoid, a ground side switching transistor and some mysterious box at the positive side. I wonder what's in the box?
Correct me if any of this is wrong or I missed anything.
PS: the pattern the solenoids are energized in reminds me strongly of Grey code, a code used (before quadrature encoders and decoder chips got cheap) to determine the position of a rotating shaft, and also to transmit parallel data over long distances without excessive interference or glitching. Basically, only one "bit" is allowed to change at a time. If it's exactly the same as grey code (I forget what the pattern for a 2 bit grey code is) it should be trivial to build a paddle shifter using 74LS or 4000 series logic chips. All that is needed is a 2-bit up/down counter (a 4 bit will also work, just ignore the upper 2 bits), a binary to grey code converter (easy to build, may exist prebuilt), and two pushbutton debounce circuits to avoid spurious shifts. Optionally, a priority encoder and some more debouncers and pushbuttons could be added and an up/down counter with preload functionality (I'm thinking of the 74LS163, personally) could be used to add 4 pushbuttons to go directly to any gear as well as allowing up/down paddle shifting.
if that isn't grey code, a PROM of some sort (I'm partial to the 27C512, but it's got a few hundred thousand bits too much for this project... I just have a few hundred of them in stock that I got for free) could be used to convert from the binary gear number coming out of the counter to the actual A340 solenoid drive signals.
