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  1. #1
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    Default How to Modify 00+ P11/B15's to Work With Older ECU's

    Getting an older ECU, OBD2 16 bit or OBD1, into 2000+ B15/P11's is not a walk in the park but it's not impossible. There is quite a bit of wiring involved, but as long as you don't go crazy reading the FSM you should be fine.

    OBD1 to OBD2 to OBD2 32bit ECU Pinouts


    There are two ways to go about it, repining and step down. If your on a B15 Repining is a must because there is no room in the ECU box for a step down harness.

    Repining the Harness
    About half of the pins should just transfer over to the OBD1 plug, the other half will need to be cut and reattached with a different ECU plug in (there are two types of plugs in the harness).


    Once it's done it will look a lot better then a step down.



    Step Down Harness
    I cut the plug of the ECU, then started soldering onto it.


    Took a bit of matching and stretching and shortening of some wires.


    Finally filled it with epoxy so that it wouldn't rattle out and come loose. I had much less epoxy before, but the RPM wire came loose. Mainly because the epoxy stuck to the heat shrink tubing not to the wire, thus the wire was still free to move. With the Epoxy being glued to the wires, it wont move at all.



    IACV-AAC Valve - Brown VE Plug
    This is the main idle control valve, you only need to take two wires out of the RR IACV. The Green/White and Brown, everything else needs to be shielded off.

    VE Plug : RR Plug
    Brown/Yellow (BR/Y) : Green/White (G/W)
    Light Blue (SB) : Brown (BR)



    You will need to extend it to reach to the VE IACV


    IACV-FICD Valve - Purple VE Plug
    This valve is used to give additional air to raise the idle while your AC is on.

    VE Plug : RR Plug
    Blue/Red (B/R) : Blue/Red (B/R) (Post Relay, run a wire from AC compressor to FICD plug)
    Yellow (Y): Ground to intake manifold (ECU ground)



    Splice the Yellow wire to the ECU Ground


    The Blue/Red wire runs from the AC compressor to the relay.


    Splice a new wire into the Blue/Red wire post relay before the compressor. This wire will need to be stretched to the purple VE plug.






    MAF Plug
    5 Volt Read - Blue
    Positive - White
    Ground - Green
    Red - Isolate and shield off.



    TPS Sensor Power - Low Voltage
    On P11/B15's the TPS Power wire is used for multiple sensors, while folder older had a pretty much dedicated power source for the TPS (99 Sentra's and 99 G20's share the TPS power with other sensors too). The wire color is P/L, or in English, Pink with Blue stripe.



    I kept on having issues with my TPS voltage being too low. After much research I finally was able to pint out the extra sensors that where using up the power. Basically older ecu's are not designed to provide the extra power that newer cars require.

    P11/B15 Sensors
    • Refrigerant Pressure Sensor - Keep this one, needed for AC usage
    • Absolute Pressure Sensor - Disconnect, located next to the MAF
    • Evap Control System Sensor - Disconnect, located in the rear of the car near the vapor canister

    • MAF - This is the red wire that you should have shielded earlier


    Coolant Sensor
    I was able to successfully use OBD2 coolant sensor with OBD1 ECU, no change needed here!
    Last edited by Vadim; 12-09-14 at 09:52 PM.
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  2. #2
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    Updated with new diagrams and TPS low voltage fix.
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    Awesome write-up Vadim. I am trying to wire up my VE AAC (Brown plug) right now, but I have two green and white wires coming from my b15 iACV harness so I don't know which one to use. They are the exact same colour wires, they are from the top and bottom ports on the middle of the plug? Any ideas which one I need?? I found the required brown plug.

    Edit: It appears as though both green/white wires are 12V +. Hopefully I'm right!
    Last edited by B15NEOVVL; 10-23-11 at 07:58 PM.

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    vadim,great write up. im using this soon.
    you used a RR harness, for an b13 ecu, for a ve correct? what are the differences between the VE (you did) and p11 usdm RR, RR Intake manifold, RR TPS ect(all RR stock) to step down to a b13 ecu in this write up.r? All on stock RR harness? i dont understand fully what your doing with the RR iacv, aside from extending it to reach the VE connection.

    when you cross pinned the ecu plugs from the RR to the B13... did you simply match the numbers from each plug and wire them? or did you comb true the fsm, and match the pins individually based on the purpose of each pin between the b13 and 00+p11? if the latter is true then the only discrepancy is the coolant sensor? thats only changed bc the plug is different right? no other sensors need to be changed? just seems too easy, i rather call you and ask. i cant seem to convey what i really want to ask but i hope this makes sense
    im trying to use a rr harness, for a rr engine for a b13 ecu. thanks for your time i hope you do answer my 21 questions haha
    Last edited by Dema; 04-29-12 at 07:00 AM.
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    Man that is a lot of work. Is there no other way to utilize the newer ecu's with something else instead of doing all this. My car is DD and I don't want to get this ridiculous with it but the governor is lame.
    93 Se-R The New Project 01 Sentra SE The DD
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    ^ its the only way.
    Another way is to swap your IMout for a LP B chasis I'M and use a B14 ecu plug. Its basicly the same thing as this^ or go stand alone system
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  7. #7
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    Quote Originally Posted by Dema View Post
    vadim,great write up. im using this soon.
    you used a RR harness, for an b13 ecu, for a ve correct? what are the differences between the VE (you did) and p11 usdm RR, RR Intake manifold, RR TPS ect(all RR stock) to step down to a b13 ecu in this write up.r? All on stock RR harness? i dont understand fully what your doing with the RR iacv, aside from extending it to reach the VE connection.

    when you cross pinned the ecu plugs from the RR to the B13... did you simply match the numbers from each plug and wire them? or did you comb true the fsm, and match the pins individually based on the purpose of each pin between the b13 and 00+p11? if the latter is true then the only discrepancy is the coolant sensor? thats only changed bc the plug is different right? no other sensors need to be changed? just seems too easy, i rather call you and ask. i cant seem to convey what i really want to ask but i hope this makes sense
    im trying to use a rr harness, for a rr engine for a b13 ecu. thanks for your time i hope you do answer my 21 questions haha
    Follow those steps to go from RR engine and harness to VE engine and RR harness. For RR harness and engine with B13 ECU, steps are going to be similar, you will need to find what to do with the IACV, B13 ECU wont know how to handle the RR IACV. It might involve you getting a Low Port intake manifold and using that.

    For the step down, follow the document which tells you what wire is to go where. It's an involved process but has been working pretty well for me. My car runs just like it had a B13 ECU from the factory.


    Quote Originally Posted by Dema View Post
    ^ its the only way.
    Another way is to swap your IMout for a LP B chasis I'M and use a B14 ecu plug. Its basicly the same thing as this^ or go stand alone system
    Even if you go standalone, no one makes a 32 bit plugs. Which is sad because SE-R Spec V's use the same plug as us.
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    What about a piggy back like emanage? Not sure if that allows to adjust rev limit and mph though. I know miko told me before he had used it on a car and make like 300 something hp.
    93 Se-R The New Project 01 Sentra SE The DD
    96 G20 Sold*99 Sentra SE-L Sold 13.0227@113mph
    *94 Sentra Se-R Sold SOLD*95 200sx Se-R Sold
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    Quote Originally Posted by LikeTheMovies View Post
    What about a piggy back like emanage? Not sure if that allows to adjust rev limit and mph though. I know miko told me before he had used it on a car and make like 300 something hp.
    You can, but I am against piggy back's simply because they fight the stock ECU. But it is the simplest way to make a few changes.
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    12 Outback 2.5i Premium - Stock

  10. #10
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    I am building a standalone system to run this car No mod's to Harness No intake manifold swapping !!! I just wanted to thank you for posting the wire colors and pin out for the 32bit ECU
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