lmdew Posted April 5, 2008 Share Posted April 5, 2008 Update: 1) I grounded pin 50 of the ECU (B84) so the ECU now is in the manual transmission mode. There was no wire in the connector at pin 50 so I installed one and put it to ground at the ECU mounting bracket. 2) The ECU is now looking for the neutral sw, which should be pin 78 of the ECU (B84) with 5.0+- 0.5 volts in neutral. I back probed the connector at ping 78 and there is 0 volts. I thought this voltage would be coming from the ECU. HELP with 2) if you have info. Thanks, Larry ______________________________________________________________________ To make a long story short, I put a 97 Impreza 2.2 standard (Engine and Trans) into a 95 Legacy Auto. It runs great but the CEL comes on with P0403 and P1702. I tried the 97 ECU but the car would not start. Anyone figured out how to fool the ECU to thinking the EGR is still there? ECU wiring details would be great, I don't have them. Thanks, in advance! Link to comment Share on other sites More sharing options...
EVOthis Posted April 5, 2008 Share Posted April 5, 2008 ive been waiting for a question like this to surface (is there any way to trick the ECU into thinking the EGR is still there?)...im not that smart...but im very intrested to hear the replies..... Link to comment Share on other sites More sharing options...
edrach Posted April 5, 2008 Share Posted April 5, 2008 Did you use the original intake manifold on the donor engine? Everything the original ECU is looking for is on the original manifold. Link to comment Share on other sites More sharing options...
OB99W Posted April 5, 2008 Share Posted April 5, 2008 [...]Everything the original ECU is looking for is on the original manifold.What is it on the intake manifold that will resolve the P1702? Link to comment Share on other sites More sharing options...
lmdew Posted April 5, 2008 Author Share Posted April 5, 2008 No, the 95 engine complete with manifold and sensors went into the 99. The 97 engine, complete with manifold and sensors went into the 95. The 97 block does not have the EGR port machined and the Manifold has the EGR blanked off. Link to comment Share on other sites More sharing options...
idosubaru Posted April 5, 2008 Share Posted April 5, 2008 what you want to do on the 1995 is keep your 1995 ECU and find out how the ECU knows it's an automatic or manual trans vehicle. you probably know that in 1995 the automatics had EGR and the manuals did not. but Subaru was smart and the ECU's are identical between the two, so the 1995 ECU can distinguish between the two and will "ignore" the EGR for the manual trans equipped EJ22's. right now it still thinks it's an automatic. find out which pin is the manual trans designator for the ECU and appropriately ground or remove it (not sure which way it works). the XT6 is the same way....ECU's are completely interchangeable as the ECU "senses" which transmission it has based on one pin. you just need to backwards engineer it to "think" it's seeing a manual trans equipped vehicle. i hope this thread turns constructive for you because i'm looking to do the same thing. at some point i'll take a look at the FSM's, but i can't now. Link to comment Share on other sites More sharing options...
screwbaru2 Posted April 5, 2008 Share Posted April 5, 2008 Have you driven the car around yet? It might just take sometime for the ecu to "learn" that's its controlling a MT. I can't say for sure but I suspect when the ecu doesn't get any AT signals it'll change to MT mode and not be looking for a egr signal. You'll still have to clear the codes but they won't come back. Worth a try, driving it won't hurt it. If you have driven it for awhile try clearing the codes, you might get a nice surprise. Or not. Good luck. Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted April 5, 2008 Share Posted April 5, 2008 I think the legacy guys over at Legacy Central run into this problem when they do a Auto to 5spd conversion. They need to trick the ECU into thinking its still an automatic or somehow tell it is no longer an auto. But these are OBD1 cars. Link to comment Share on other sites More sharing options...
lmdew Posted April 5, 2008 Author Share Posted April 5, 2008 Yes, I've driven the car about 150 miles, on and off over 15 times. I've cleared the codes 2x now. I'll keep on doing it and see what happens. Legacy777 swap page is good, but yes its for OBDI not OBDII. The search continues. Thanks for the ideas! Link to comment Share on other sites More sharing options...
screwbaru2 Posted April 5, 2008 Share Posted April 5, 2008 Imdew checkout porc's post on this thread: http://www.ultimatesubaru.org/forum/showthread.php?t=84900&highlight=P1702 About half way down you'll see trans type test AT or MT and a reference to the trans ID circuit # although I don't a picture of which pin it is. Maybe porc can get you more info Link to comment Share on other sites More sharing options...
edrach Posted April 5, 2008 Share Posted April 5, 2008 What is it on the intake manifold that will resolve the P1702?Nothing. P1702 is automatic transmission signal is low. I don't know why you should get this if you still have the AT installed. I'd start looking for a broken wire or bad connection that might have occurred with the engine swap. You're looking for connector B55, pin 11 of the TCM to B84, pin 80 on the ECU. I can mail you the three pages of troubleshooting info from my FSM ('97 Impreza) which might help. Drop me a PM with an address and I'll get it off to you. Link to comment Share on other sites More sharing options...
edrach Posted April 5, 2008 Share Posted April 5, 2008 No, the 95 engine complete with manifold and sensors went into the 99. The 97 engine, complete with manifold and sensors went into the 95. The 97 block does not have the EGR port machined and the Manifold has the EGR blanked off. I'm certainly not the expert here, but I've always understood that the EJ22 blocks are all the same and the big difference is that the manifold sensors are the main change. Swap an engine, use the original manifold to keep the ECU happy. If that's not the case let us know how you resolved this. See my other post about the P1702. From my reading of the FSM, the signal the ECU is looking for is 1 volt; if you also installed a manual transmission, you'll need to rig up a way to get a 1 volt signal to the ECU to keep it happy. Link to comment Share on other sites More sharing options...
subaru360 Posted April 5, 2008 Share Posted April 5, 2008 what you want to do on the 1995 is keep your 1995 ECU and find out how the ECU knows it's an automatic or manual trans vehicle. you probably know that in 1995 the automatics had EGR and the manuals did not. but Subaru was smart and the ECU's are identical between the two, so the 1995 ECU can distinguish between the two and will "ignore" the EGR for the manual trans equipped EJ22's. right now it still thinks it's an automatic. find out which pin is the manual trans designator for the ECU and appropriately ground or remove it (not sure which way it works). the XT6 is the same way....ECU's are completely interchangeable as the ECU "senses" which transmission it has based on one pin. you just need to backwards engineer it to "think" it's seeing a manual trans equipped vehicle. i hope this thread turns constructive for you because i'm looking to do the same thing. at some point i'll take a look at the FSM's, but i can't now. This is the right answer. You have to look at the ECU pinout, find the wire that the ECU uses to sense if its a manual or auto and either open or ground it, I forget which. This is the easiest way to fix your problem. Link to comment Share on other sites More sharing options...
edrach Posted April 5, 2008 Share Posted April 5, 2008 This is the right answer. You have to look at the ECU pinout, find the wire that the ECU uses to sense if its a manual or auto and either open or ground it, I forget which. This is the easiest way to fix your problem.According to the FSM, the automatic signal is 1 volt so grounding it sounds like the answer. Check my other post for the pin outs. Link to comment Share on other sites More sharing options...
subaru360 Posted April 5, 2008 Share Posted April 5, 2008 According to the FSM, the automatic signal is 1 volt so grounding it sounds like the answer. Check my other post for the pin outs. Good info. I wasn't sure what input the ECU needed. If you do need exactly one volt, it should be possible to put a resistor in the wire to drop the voltage down. Link to comment Share on other sites More sharing options...
OB99W Posted April 6, 2008 Share Posted April 6, 2008 What is it on the intake manifold that will resolve the P1702? Nothing. P1702 is automatic transmission signal is low.[...] That's what I thought, but figured maybe I was missing something when you said "Everything the original ECU is looking for is on the original manifold.". Link to comment Share on other sites More sharing options...
edrach Posted April 6, 2008 Share Posted April 6, 2008 That's what I thought, but figured maybe I was missing something when you said "Everything the original ECU is looking for is on the original manifold.".I mis-read his original post and didn't realize that he had also swapped transmissions. Generally speaking, if you swap engines use the original manifold so as not to confuse the ECU. Link to comment Share on other sites More sharing options...
lmdew Posted April 25, 2008 Author Share Posted April 25, 2008 Updated initial post, help is needed! Thanks Link to comment Share on other sites More sharing options...
subaru360 Posted April 25, 2008 Share Posted April 25, 2008 Updated initial post, help is needed! Thanks I'm a little confused as far as what you want to do with the signal for the neutral switch. If the ECU now thinks it's a 5 speed, it shouldn't need a signal from the park/neutral switch. But anyway, if you think it needs 5 volts there, just pick up 12 volts from somewhere and add a resistor as needed to lower the voltage to 5. Link to comment Share on other sites More sharing options...
lmdew Posted April 26, 2008 Author Share Posted April 26, 2008 The ECU looks for the switching of 5 volts in neutral, 0 volts when in gear. I'm thinking the 5 volts should be coming from the ECU and when grounded through the neutral sw it's 0 volts. I just don't know why the 5 Volts is not at pin 78. Link to comment Share on other sites More sharing options...
johnceggleston Posted April 26, 2008 Share Posted April 26, 2008 larry, in your first post you said the 97 TCU didn't work because the car wouldn't start, did it not turn over, starter didn't engage or would it turn over and not fire? i was wondering if the 97 TCU didn't 'see' the neutral switch. maybe the pinout changed slightly on the connector. it seems the 97 tcu would be a better choice for the trans but would it be more work getting it to run? i didn't re-read the bulk of this thread so forgive me if this has been covered. Link to comment Share on other sites More sharing options...
lmdew Posted April 26, 2008 Author Share Posted April 26, 2008 The pin out is different from the 95 ECU to 97 ECU so I put the 95 ECU back in. I'm going to cut wire 78 today, I'm thinking it may already be grounded somewhere and if its cut then I may see the 5.0 volts from the ECU. If that works, then all I have to do is wire it to the neutral sw. I think you ment ECU not TCU in the post above. Thanks for the info. Link to comment Share on other sites More sharing options...
korrupt66 Posted April 26, 2008 Share Posted April 26, 2008 I don't know if this will help but I have an ECU from a 96 legacy manual. Link to comment Share on other sites More sharing options...
lmdew Posted April 26, 2008 Author Share Posted April 26, 2008 It's good. I cut wire 78 about a foot from the ECU, 4.75 volts out of the ECU. Wired it to the neutral sw and the sw to ground. The ECU is getting what it wants, no CEL. Thanks for the help. Link to comment Share on other sites More sharing options...
edrach Posted April 26, 2008 Share Posted April 26, 2008 Talk about perseverance; good job. Link to comment Share on other sites More sharing options...
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