LPGsuperchargedBrumby Posted July 22, 2009 Share Posted July 22, 2009 (edited) anyone know what input signals the 4eat tcu needs to know to change at the right times? TPS and RPM....is there anything else that the TCU needs? the reason i ask is that i am trying to figger out if its possible to get a 4EAT to work behind a carbureted EJ22... any ideas would be appreciated.... Edited July 22, 2009 by LPGsuperchargedBrumby Link to comment Share on other sites More sharing options...
idosubaru Posted July 22, 2009 Share Posted July 22, 2009 if you bolt the 4EAT up without any computer it'll run just fine...in 3rd gear and "locked" 4WD! it can be done because people have made their own paddle shifters/controllers for them. problem is that information is not widely available. there's a thread a few months old that talks a lot about building a paddle shifter and someone in that thread was well versed in that kind of stuff, might want to find that thread. the main thing it uses is the TPS. you could probably keep enough of the wiring harness from that to keep input to the trans? Link to comment Share on other sites More sharing options...
Gloyale Posted July 22, 2009 Share Posted July 22, 2009 TPS, RPM, and Speedo. Link to comment Share on other sites More sharing options...
monstaru Posted July 22, 2009 Share Posted July 22, 2009 IPT makes a controller. here is there webspace: http://www.ipttrans.com/subaruauto.shtml#main cheers, brian Link to comment Share on other sites More sharing options...
LPGsuperchargedBrumby Posted July 24, 2009 Author Share Posted July 24, 2009 hmmm TPS RPM an Speedo....famous last words maybe....but that don't sound too complicated to get to work Link to comment Share on other sites More sharing options...
4x4_Welder Posted July 24, 2009 Share Posted July 24, 2009 Does the manual valve work or does that just put it in a general drive position and it's all electronic from there? I'm almost wondering about using the 4EAT I have in my project, it would be nicer than a manual even though I already have an EA81 4speed. Not needing the clutch would be really nice in this application, but I would have to weld up the output since I'm only using the rear output. Maybe I'll just tuck it away, and see if a need for it turns up........... Link to comment Share on other sites More sharing options...
Gloyale Posted July 24, 2009 Share Posted July 24, 2009 Does the manual valve work or does that just put it in a general drive position and it's all electronic from there? I'm almost wondering about using the 4EAT I have in my project, it would be nicer than a manual even though I already have an EA81 4speed. Not needing the clutch would be really nice in this application, but I would have to weld up the output since I'm only using the rear output. Maybe I'll just tuck it away, and see if a need for it turns up........... It needs the valve to be in the correct posistion, as well as having the electronic signal from the switch. It is easy because the switch mounts directly to the side of the trans, so no internal mounting. Someone else built a paddle shifter, but IDK how they got around the valve issue. My Legacy 4eat won't engine brake in 1st hold, unless the lever is all the way down to 1 position. Link to comment Share on other sites More sharing options...
idosubaru Posted July 24, 2009 Share Posted July 24, 2009 hmmm TPS RPM an Speedo....famous last words maybe....but that don't sound too complicated to get to work i'd probably try and get my hands on an entire 4EAT wiring harness or at the very least the TCU input plugs if you're cool with doing some wiring. actually the speedo should work itself out, that's part of the trans and is cable driver to the instrument cluster. so that feed should be simple. engine side stuff then should be TPS and RPM. Link to comment Share on other sites More sharing options...
Gloyale Posted July 24, 2009 Share Posted July 24, 2009 hmmm TPS RPM an Speedo....famous last words maybe....but that don't sound too complicated to get to work And of course the rest of the TCU wiring. But those 3 signals are all that;s needed form outside the Trans/TCU Link to comment Share on other sites More sharing options...
4x4_Welder Posted July 24, 2009 Share Posted July 24, 2009 Anybody know how it would behave with just an RPM input, would it just upshift quick? Maybe I could rig a switch on the throttle linkage to toggle between a low resistance and a high resistance to imitate a TPS on my carbed EA81. I guess I should set all this off to the side, might come in handy. I'll have to see how the manual works first I guess. Link to comment Share on other sites More sharing options...
presslab Posted July 26, 2009 Share Posted July 26, 2009 anyone know what input signals the 4eat tcu needs to know to change at the right times? TPS and RPM....is there anything else that the TCU needs? the reason i ask is that i am trying to figger out if its possible to get a 4EAT to work behind a carbureted EJ22... any ideas would be appreciated.... Yeah TPS and RPM from the engine. The rear speed sensor will come from the 4EAT; the front is from the instrument cluster, you'll need to rig something up. You'll also need the gear selector switch inputs as well as brake pedal. Someone else built a paddle shifter, but IDK how they got around the valve issue. My Legacy 4eat won't engine brake in 1st hold, unless the lever is all the way down to 1 position. It's true, the low clutch is only engaged when the lever is moved. The low clutch locks up the OWC for 1st gear. However it's possible to electronically select gears 1-3 with the lever there. Otherwise there is still engine braking in 2-4 by using the Shift Solenoid 3. Link to comment Share on other sites More sharing options...
kiwishooter Posted August 7, 2009 Share Posted August 7, 2009 Mostly correct as the signals that are fed direct into the trans ECU are TPS, front and rear speed sensor, Inhibitor switch, Engine ECU signals, FWD switch (fuse), Brake switch, and AT hold from what I recall. Outputs from the trans ECU are trans temp, power, Manual, FWD lights, pressure, TC lock up, over run, 2x shift, and transfer clutch solenoids, and Check connector. So when you look at all this it would be easy to fit an auto and also fit the trans ECU with wiring the only thing to figure out is what the signal from the engine ECU to the trans ECU is, possibly rpm only way to find out is monitor the signal and see what it corresponds too. The easiest way to do it would be to get the wiring harnes, trans ECU and other related components from a doner vehicle. A trans would be easy I have about 30, some are none turbo, others are single turbo, some twin turbo, and a couple of two wheel drive. Turbo trans are usually 4.111 ratio. The none turbo and single turbo disengage the transfer clutch when the FWD sw (fuse) is installed while the twin turbo lock up the transfer clutch when the switch (fuse) is installed. Link to comment Share on other sites More sharing options...
Gloyale Posted August 8, 2009 Share Posted August 8, 2009 So when you look at all this it would be easy to fit an auto and also fit the trans ECU with wiring the only thing to figure out is what the signal from the engine ECU to the trans ECU is, possibly rpm only way to find out is monitor the signal and see what it corresponds too. It's already been established. TCU monitors TPS voltages. What I have wondered is, woudl the TCU be capable of reading a TPS signal without having an ECU hooked up tho the TPS to actaully send the signal voltage out. Link to comment Share on other sites More sharing options...
presslab Posted August 8, 2009 Share Posted August 8, 2009 It's already been established. TCU monitors TPS voltages. What I have wondered is, woudl the TCU be capable of reading a TPS signal without having an ECU hooked up tho the TPS to actaully send the signal voltage out. It should be possible. The TPS needs "Power (sensor)" of +5.0V from the ECU. A simple voltage regulator LM7805 from Radio Shack and a couple capacitors should be all that is needed to replace this. http://www.radioshack.com/product/index.jsp?productId=2062599 Link to comment Share on other sites More sharing options...
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