wagonist Posted April 11, 2017 Share Posted April 11, 2017 I've seen it mentioned several times about when you swap the 4EAT to a 5speed, that the ECU throws a CEL. But nothing about how to fix this problem. I'm looking to do this shortly & would rather get it right because I want the CEL to work properly. Car is 1990 model with EA82T Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 11, 2017 Share Posted April 11, 2017 IIRC, it had to do with the neutral switch on the trans and the fix was wiring a relay to the clutch pedal switch in some fashion. I remember reading it quite some time ago, but not the exact details nor do I remember seeing a post on the the actual fix. It was one of those, 'You could do this' scenarios. Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 11, 2017 Author Share Posted April 11, 2017 Are you referring to the neutral switch on the manual trans or the auto? I think the auto gets it's neutral signal from the shifter. I've been doing some searching & came up with something similar for other manufacturers. I think it was have the wire to "D" hooked up, and then when the clutch was pressed, this got switched to a "N" signal. But then this meant the "N" signal came in every time you changed gears... Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 12, 2017 Share Posted April 12, 2017 Right, but the ECU doesn't care how many times neutral is selected as long as it's not selected when it sees engine load along with increase in RPMs and speed. Also, if it sees either D or N constantly pulled high, low or open, it will set a code. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 12, 2017 Share Posted April 12, 2017 ECU's are not transmission dependent. There is not "automatic ECU" or "Manual ECU". You can install an ECU from a manual vehicle into an automatic and the other way around all day long with zero issues because they're the same ECU. There's an identifier pin on the harness that "tells" the ECU what transmission it is - so you just need to mimic that. I don't know if this is correct at all, or for your car specifically, but for example it's mentioned and talked about here: http://www.ultimatesubaru.org/forum/topic/148630-automatic-to-manual/ Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 19, 2017 Author Share Posted April 19, 2017 That link refers to SPFI & 3AT, neither are relevant to my vehicle. I'm aware that the ECUs are identical & that there is something in the loom that "tells" it whether the engine is connected to an auto or manual. Info about that "telling" is what I'm trying to find out. Skishop69, can you please clarify what your statement about D or N signal being pulled one way all the time. In my mind, having D selected all the time shouldn't be a problem as once a car is started, it would be expected that the trans is in D for 99.9% of the trip. I'm worried about hooking up the clutch to a N signal, as it might confuse things if a N signal is introduced whilst in motion as you change gears (even under no load) Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 20, 2017 Share Posted April 20, 2017 Being pulled high or low refers to giving a signal voltage (high) or a signal ground (low) depending on which the ECU is looking for. Some systems even monitor the actual voltage change, so not hooking it up at all is an open and the system sees nothing when it is expecting to see something and will set a code. Setting it up to see drive all the time won't work headache free. The system 'can't' see D selected at start up or you will get a code set and possibly a no start depending on the vehicle. Also, selecting D all the time causes the ECU to use a different fuel map so your N, unloaded idle fueling would be richer possibly causing an emissions issue. If that's an issue down under. It's nothing you'd really notice though unless it set a code. Selecting neutral all the time will also set codes and again cause emissions issues due to fuel map differences. Since the ECU's are the same, then there will be a single wire that needs to be grounded or supplied with voltage to tell the system which trans is in use. You will have to examine the manual ECU pinnout and compare it to the auto ECU pinnout to find that one wire then trace it to see whether it goes to ground, voltage or possibly back to the ECU itself and undo whatever signal tells the ECU it's an auto and then you don't have to worry about D or N. Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 20, 2017 Author Share Posted April 20, 2017 Thanks. Was on the same line of thinking, but wanted to check. But still confused how having the D signal hooked up whilst driving would cause an error. Agree however that need to have N or P signal when starting. Ultimately, nodding the loom so the ECU thinks its got that correct trans would be best. Any ideas where to get diagrams to suit 90 model? Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 20, 2017 Share Posted April 20, 2017 If I have time at work today I'll pull the schematics and see if I can tell you which wire it is. If not, maybe someone here could scan and email them. There's always Google. Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 20, 2017 Author Share Posted April 20, 2017 cheers. That would be helpful. I've done a lot of other research as well (I'm not one of those who expects others to help me without already trying to help myself first) & come up with nothing. Main problem is I've got a combination of engine & trans that wasn't readily available in this country. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 21, 2017 Share Posted April 21, 2017 OK, so I had a slow day today so I had time to pull the schematics and look over them. Going on what you stated about having an EA82 and a 4EAT with no separate trans ECU, here are the things I know you'll have to do. Pin 15 of the ECU, which is a yellow wire with a blue tracer will have to be wired to one terminal on the clutch switch on the pedal box. Pin 42 which is a solid brown wire needs to be wired to the other terminal of the clutch switch. The trans range switch (TRS or Inhibitor) needs to be modified. The yellow wire with a green tracer needs to go to one of the pins on the neutral switch of the manual trans. The solid brown wire at the TRS needs to go to the other terminal of the neutral switch. You can either build a small jumper harness to connect them, remove the terminals from the connector housing and attach them directly to the neutral switch or cut the wires and solder on the neutral switch connector if you have one. This is what I would do. Be sure to use heat shrink tubing over the solder joints then tape the wires up for security. Next, back to the ECU. Pin 13 which is a yellow wire with a red tracer needs to be cut. This is the D (drive) signal for (AT) only. Pins 1 (light green wire) and 16 (light green wire with a red tracer) go to the kick-down control and kick-down monitor devices and also need to be cut. These circuits may provide feedback to the ECU that it doesn't need for the (MT). Now things get a little tricky. This is what I believe needs to happen based on the schematics for the (AT) portion tracking all connections having anything to do with (AT) only. Pin 32 which is a solid brown wire, needs to be cut. This is why I think this is our '(AT) selection' wire: The ECU pinnout has this wire labeled as 'Test mode connector (used at line end only)'. That's all fine and dandy except that it does in fact go to ground (GND). Except that with Subaru and almost every other manufacturer in the world, a GND to complete a POWER circuit is always black. A black wire with a tracer (or any color other than black labeled GND) is a return GND circuit for a sensor, not power (load) supply purposes. This is pretty much universal with automotive wiring. Therefore, this wire is not a power supply GND for the ECU and not necessary. This wire goes into the harness and then taps into the pin 42 wire which is also brown and is the switch/sensor GND for the clutch and neutral switches. It (pin 32) is also labeled (AT) on the schematic and DOES NOT got to ANY (AT) sensors or controls. Now this is based on a logical interpretation of their schematic and I'm not the engineer who came up with the system so there is a margin of error here. I do know that nothing will be damaged by cutting this wire. There is another wire that also comes into question. Pin 30 which is also a brown wire and is labeled GND in the schematics. It also goes into the harness and taps into the pin 42 brown wire and then to the black check connector but has no other function. Since it goes to the check connector, I'm pretty sure we don't need to do anything with it but cutting it won't hurt anything either. It's all on you now. lol Any wire you choose to cut at the ECU, make sure you cut it 3"-4" out from the connector so you have room to splice it back together if necessary. I would start with wiring the clutch and neutral switches, cut 13 and 32 and then see if 1 and 16 really need to be cut. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 21, 2017 Share Posted April 21, 2017 That link refers to SPFI & 3AT, neither are relevant to my vehicle. Gotcha, I saw "ECU CEL" in your title and assumed you thought the ECU's were different. I called that link an "example" that the ECU doesn't matter....but clearly you knew that... I'm going to guess the wiring diagram and FSM is hard to find? 1 Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 23, 2017 Author Share Posted April 23, 2017 (edited) sorry skishop69, I've got a separate TCU for the auto trans. All of the EA82's do. I thought it wasn't til much later that the ECU also controls the trans. Does this change anything you've posted? Awesome bit of info BTW Are you able to scan the schematic & post it up? Edited April 23, 2017 by wagonist Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 24, 2017 Share Posted April 24, 2017 According to the schematics, there were EA82s with an AT and without a TCU. Not to say they're not wrong, because I've found tons of mistakes myself. Lucky for you, I also checked out the TCU version schematics. Based on what I saw there you simply, wait for it....... Unplug the TCU. OBD1 systems did not have the capability to monitor other modules to see if they were online or communicating so unplugging it should not cause a CEL. That being said, I didn't pull the TCU connector pinnout and there are about a half dozen pins not listed in the control schematics for the TCU. I will check the pinnouts tomorrow at work. There is a possibility that there may be a line to the ECU that needs to be grounded. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 26, 2017 Share Posted April 26, 2017 Couldn't find a pinnout for the TCU. Based on what I saw though, unplugging it should do you. Check pins 6,7,8 & 15 and see if there are any wires or if they're blank and let me know. I think you may have to wire as I stated above though because the ECU is still the same. 1 Quote Link to comment Share on other sites More sharing options...
wagonist Posted April 26, 2017 Author Share Posted April 26, 2017 Despite the ECU not being able to check whether anything is attached, there are wires in the loom "telling" the ECU that it's connected to an auto. So when it doesn't get the correct signals, it throws the CEL. Maybe this applies whether it's connected to a 3AT or 4EAT, but I'd be surprised if the series 2 (87.5 -) turbos had anything but the 4EAT attached. I'll check the pins like you've said. Can you tell me which way the pins are numbered so I'm checking the correct wires? Quote Link to comment Share on other sites More sharing options...
skishop69 Posted April 26, 2017 Share Posted April 26, 2017 Here's the scan for the TCU and thew ECU. IMG.pdf IMG_0001.pdf 1 Quote Link to comment Share on other sites More sharing options...
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