Geoff F Posted August 22, 2020 Share Posted August 22, 2020 Hey all. I swapped engines in my 2009 Subaru Impreza 2.5I with a JDM boxer engine. After the swap I went through some of the codes (there are a few) and one that stuck out is P1491 which is a PCV function problem. The JDM motor I threw in didn't even have the sensor itself that connects somewhere on the intake so the ECU will never get a signal from the boxer engine wiring harness. I've read online that the sensor is essentially useless as it only checks for voltage making sure the thing is plugged in. Can I just rig up a little jumper cable between the two pins on the cars ECU so it completes the useless circuit? If so, does anyone have the pinout for the 09 Impreza 2.5I? The car is also throwing some ABS codes (0316, C0057. C0072) but I wanna take this one step at a time. Thanks! Quote Link to comment Share on other sites More sharing options...
wtdash Posted August 22, 2020 Share Posted August 22, 2020 (edited) Hi Did you (not) reuse your original Intake manifold? That would eliminate a lot of the 'unknowns' - at least that's what others do....unless it incompatico w/the JDM version. Otherwise, go here for the FSM. I've not dealt w/any Subarus newer than '04 , so not any help on the ABS stuff...but if you have 0 codes before the swap, so may be those are 'phantom codes'? Older Subies were notorious for throwing a barrage of codes when really only one issue was occurring. Fix that one and the rest vanished. GL, Td Edited August 22, 2020 by wtdash Quote Link to comment Share on other sites More sharing options...
Geoff F Posted November 19, 2020 Author Share Posted November 19, 2020 Thanks for the FSM Td! Sorry I'm so late to respond, kinda got lost on this project. I did not use the original intake manifold though, would have been a great idea. The only code I'm getting now is the P1491 code because the PCV sensor is not physically there, But I skimmed through the manual and found that the PCV sensor is connected to A30. Is this the pin on the ECM harness that it plugs into? I'm no electrical expert lol. I've attached some pictures of what I'm talking about. Thanks! Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted November 19, 2020 Share Posted November 19, 2020 All they are is a flat metal blade jumper that connects the two pins. You can just hook the wires together in the harness and it will shut off the code. GD 1 Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 11, 2021 Author Share Posted January 11, 2021 On 11/19/2020 at 3:01 PM, GeneralDisorder said: All they are is a flat metal blade jumper that connects the two pins. You can just hook the wires together in the harness and it will shut off the code. GD GD, Understood, but the sensor is not physically there (or at least the wires for it were cut and are hidden somewhere in the harness). If I had to make a jumper, it will have to come directly from the pins on the ECU so I have to figure out exactly where those two pins are. Thanks, Geoff Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 11, 2021 Author Share Posted January 11, 2021 This is an updated thread. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 11, 2021 Share Posted January 11, 2021 The wires should be at the large connector for the main harness to manifold harness at the back near the passenger side of the bell-housing. Get a pinout and wire colors and just jumper them at that point. It's probably just a single pin on the ECU to a ground. GD Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 12, 2021 Share Posted January 12, 2021 In the picture you posted, the large Connector B21 Pin 10 should be a Pink wire on the engine side of the plug. On the vehicle side it is Yellow/red going to the ECU. Is there a Pink wire on Pin 10 or is it empty? And is there a Yellow/red on the other half going into the cabin? On the connector you highlighted E61 Pin 2 goes to (A30) B134 Pin 30 and E61 Pin 1 goes to ground. You will see that on the next page following the W. On this page the W is on the right side, on the next page it will be on the left. Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 15, 2021 Author Share Posted January 15, 2021 On 1/11/2021 at 10:54 PM, Rampage said: In the picture you posted, the large Connector B21 Pin 10 should be a Pink wire on the engine side of the plug. On the vehicle side it is Yellow/red going to the ECU. Is there a Pink wire on Pin 10 or is it empty? And is there a Yellow/red on the other half going into the cabin? On the connector you highlighted E61 Pin 2 goes to (A30) B134 Pin 30 and E61 Pin 1 goes to ground. You will see that on the next page following the W. On this page the W is on the right side, on the next page it will be on the left. Let me take a step back as I now have a more clear wiring diagram for the PCV valve. However, it depends on the year of the car/engine. My car is a 2009 but the JDM motor appears to be from a 2007. I called JDM and the only thing they could tell me is to check under the oil fill cap for the year which indicates it is a 2007 motor (not very reliable, I know). So, the 07' manual shows (as GD mentioned) that the wire runs out of pin 4 and goes to a ground which would be very nice. The 09' manual shows the wires jump between pin 41 and 45. All of the previously mentioned pins are occupied on the engines wiring harness which makes me very hesitant to start cutting away without knowing what is what. Pin 4 is a pale yellow, pin 41 is yellow/red, and pin 45 is orange. My impatience tells me to assume its an 07' harness and to simply ground out the wire from pin 4 but logic is questioning how the only discrepancy between the two years is the PCV valve pin location. Wouldn't my car be throwing a ton of other codes assuming the pinouts are pretty different between years? I appreciate all of the help. Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 15, 2021 Share Posted January 15, 2021 The diagram you posted for 09 is for the TURBO model. The 07 and 09 NON-TURBO are like the 07 you posted. Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 15, 2021 Author Share Posted January 15, 2021 Ah good catch! When I look at the two manuals the 07 has "EN(STI)" in the footer and the 09 has "EN(H4DOTC)" in its footer which proves you correct. That is some great news. Is there anything special I need to consider before going ahead with the job? My plan is to just cut the wire coming out of pin 4, splice a similar gauge wire into it, and ground it wherever. Thank you!!! Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 16, 2021 Share Posted January 16, 2021 (edited) 6 hours ago, Geoff F said: Ah good catch! When I look at the two manuals the 07 has "EN(STI)" in the footer and the 09 has "EN(H4DOTC)" in its footer which proves you correct. That is some great news. Is there anything special I need to consider before going ahead with the job? My plan is to just cut the wire coming out of pin 4, splice a similar gauge wire into it, and ground it wherever. Thank you!!! On the engine side of Connector B21----for the 07 model- PIN 4 is used on the Turbo model and STI. The wire color is Lavender/Red stripe. The Non Turbo uses PIN 10. The wire color is Black/Lavender stripe. I don't know why the different pins. You said the color wire on Pin 4 is a Pale Yellow. Count in from the other side of the connector and what color is it? The body side of the connector Pin 4 should be Lavender/Red stripe. That will be the pin to use. If you are not sure which one to use, I would disconnect the battery and check continuity to the ECU connector (A30) - Pin 30 on B134. The wire color there is Lavender/Red stripe on all three models. Usually looking at the wire side of a connector the pin numbers are backwards. The picture shows the pin side of the connector. On the body side of Connector B21 the 09 uses Pin 4 Lavender/Red stripe. For a test, I would poke a straight pin into the connector along side the wire, or lengthwise into the wire itself and wrap and tape a wire to it and run it to ground. Then if that works cut and splice the grounded wire onto it. Edited January 16, 2021 by Rampage Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 19, 2021 Author Share Posted January 19, 2021 On 1/15/2021 at 8:22 PM, Rampage said: On the engine side of Connector B21----for the 07 model- PIN 4 is used on the Turbo model and STI. The wire color is Lavender/Red stripe. The Non Turbo uses PIN 10. The wire color is Black/Lavender stripe. I don't know why the different pins. You said the color wire on Pin 4 is a Pale Yellow. Count in from the other side of the connector and what color is it? The body side of the connector Pin 4 should be Lavender/Red stripe. That will be the pin to use. If you are not sure which one to use, I would disconnect the battery and check continuity to the ECU connector (A30) - Pin 30 on B134. The wire color there is Lavender/Red stripe on all three models. Usually looking at the wire side of a connector the pin numbers are backwards. The picture shows the pin side of the connector. On the body side of Connector B21 the 09 uses Pin 4 Lavender/Red stripe. For a test, I would poke a straight pin into the connector along side the wire, or lengthwise into the wire itself and wrap and tape a wire to it and run it to ground. Then if that works cut and splice the grounded wire onto it. Thank you for the detailed troubleshooting. This is the body side of connector B21 on my car...should be factory made and untampered with so this could be used as basecamp. Correct me if I'm wrong, but it appears that pin 4 is occupied with a brown/blue wire. And if I count from the other side then it looks to be a solid black wire?? Am I overlooking something or just colorblind? Quote Link to comment Share on other sites More sharing options...
Geoff F Posted January 19, 2021 Author Share Posted January 19, 2021 2 minutes ago, Geoff F said: Thank you for the detailed troubleshooting. This is the body side of connector B21 on my car...should be factory made and untampered with so this could be used as basecamp. Correct me if I'm wrong, but it appears that pin 4 is occupied with a brown/blue wire. And if I count from the other side then it looks to be a solid black wire?? Am I overlooking something or just colorblind? Sorry for double posting but the 2MB size limit on attachments is making me. Here is the engine side of connector B21 (JDM's work). If I look at it backwards like you mentioned I see that pin 4 is occupied by a red/pale yellow color wire. Could this be the red/lavender wire you were referring to and I'm just seeing it different? Quote Link to comment Share on other sites More sharing options...
Rampage Posted January 19, 2021 Share Posted January 19, 2021 (edited) I have had occasions where the FSM shows the wrong wire color, but the connector pin numbers have always been correct. I had that problem when I rewired the parking light switch on our 96 Voyager to eliminate the BCM control of the parking lights. So far I have not had a problem with Subaru wire colors. I'll look at some other year manuals and see what I find. Disconnect the battery and connectors B21 and A134 at the ECM. Check for continuity from A134 Pin 30 to Pin 4 on B21. Also check it to Pin 10 on B21. It is Yellow/Red and looks like the one in your picture. I'm wondering if that is the one. Also, what color wire is on A134 Pin 30? Look at the images of the ECM connectors so you get the right one. The pictures of the connectors show the pin side of the (plastic) male connector numbered left to right. The male has a single border around it. The female either has a double border around it or an extra line on the bottom side of the image. I wouldn't cut or ground wires until we are positive it is the right one. Of course, while you are at the ECM connector A134, you could ground Pin 30 there. That would eliminate trying to find it on B21. Edited January 20, 2021 by Rampage Quote Link to comment Share on other sites More sharing options...
Geoff F Posted February 5, 2021 Author Share Posted February 5, 2021 Just got done getting to the ECM. There are 4 connectors running into the ECM and B134 is the first from left to right. I matched the pins on the connector with the image of B134 in the FSM to be sure. Pin 30 on B134 is yellow/red and it actually runs to Pin 10 on B21 (car side of harness). I checked the continuity and bingo. Although this doesn't match the FSM with the sensor running to Pin 4 on B21, it does explain why there is a vacant Pin 10 on the engine side of the harness. For starters, I am going to put everything back together and simply ground a wire coming from pin 10 on the engine side of the harness. This way if I'm wrong then no harm will be done by cutting wires. If that works then I may go back to B134 and ground it there for aesthetic purposes, but I'm not too worried about that for now. Wish me luck! 1 Quote Link to comment Share on other sites More sharing options...
Geoff F Posted March 4, 2021 Author Share Posted March 4, 2021 SOLVED! Thanks to everyone who helped me through this issue. I ended up splicing a wire into pin 10 on the vehicle side of the wiring harness and grounding it to a bolt on the engine. I checked continuity between this bolt and the negative terminal of the battery beforehand to ensure it was a good ground. I decided to splice into the vehicle side of the harness as opposed to putting a new pin on the engine side of the harness because I couldn't find a terminal/pin anywhere on the internet. The code was gone when I fired it up and its been running fine ever since. Cheers! 2 Quote Link to comment Share on other sites More sharing options...
Myco Posted March 26, 2022 Share Posted March 26, 2022 On 3/3/2021 at 7:08 PM, Geoff F said: SOLVED! Thanks to everyone who helped me through this issue. I ended up splicing a wire into pin 10 on the vehicle side of the wiring harness and grounding it to a bolt on the engine. I checked continuity between this bolt and the negative terminal of the battery beforehand to ensure it was a good ground. I decided to splice into the vehicle side of the harness as opposed to putting a new pin on the engine side of the harness because I couldn't find a terminal/pin anywhere on the internet. The code was gone when I fired it up and its been running fine ever since. Cheers! Sir can you send me a picture if how did you fixed it?PIN number 10 yellow red is positive did you put resistor to a ground? Quote Link to comment Share on other sites More sharing options...
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