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Thread: 97 M3 wiring harness horror story

  1. #26
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    Quote Originally Posted by ScotcH View Post
    I have never seen a relay next to the ECU ... is that an OBD2 thing?!?!
    97+, not on 96. Might be 98+.

  2. #27
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    Quote Originally Posted by Braymond141 View Post
    97+, not on 96. Might be 98+.
    That explains it … I've only ever worked on 96 and older
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  3. #28
    NeilM is offline Member BMW E36 M3 Expert
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    Yes, no relay there on my 96, but that year is sort of a unicorn. Anyone know what it does?

    Neil

  4. #29
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    Does anyone know if I could replace my engine wiring harness with one out of a 1995 325 manual? My concern is it's coming out of an OBD I car and into my OBD II 97. Both manual though.

  5. #30
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    I would not try to use an obd1 harness. At least some wiring differs. Not sure about the ECU harness. I have done only 1 obd1 harness install and it was years ago.

  6. #31
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    Quote Originally Posted by HotWaterMusic View Post
    Does anyone know if I could replace my engine wiring harness with one out of a 1995 325 manual? My concern is it's coming out of an OBD I car and into my OBD II 97. Both manual though.

    No, it would not work.

    Harness plug is also different on the ECU.
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  7. #32
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    Is ECS tuning the only place out there that offers a new engine harness? I can't sit around for weeks waiting for my wanted ad in the classifieds to net anything, but $1100 isn't chump change for a new one. Wish there was a 3rd option I could trust.

  8. #33
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    I would not buy new. Too much money. If you cannot wait to buy a used one for $100, try a parter like asmodus.

  9. #34
    NeilM is offline Member BMW E36 M3 Expert
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    Quote Originally Posted by HotWaterMusic View Post
    Is ECS tuning the only place out there that offers a new engine harness? I can't sit around for weeks waiting for my wanted ad in the classifieds to net anything, but $1100 isn't chump change for a new one. Wish there was a 3rd option I could trust.
    Turner offers them, but that's really the same company. You should post a request in the Track, Auto-X & Drag Racing forum here. That's how I found my last one. People have parts lying around that they're not bothering to offer for sale, but will if someone comes looking.

    Otherwise yes, try to find one from an auto recycler, and yes, it needs to be an OBD2 harness.

    Try calling Zionsville Autosport (Indianapolis area) at 317-873-3216. They specialize in used BMW parts and know what they're talking about.

    Neil
    Last edited by NeilM; 05-06-2019 at 02:22 PM.

  10. #35
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    Quote Originally Posted by NeilM View Post
    Turner offers them, but that's really the same company. You should post a request in the Track, Auto-X & Drag Racing forum here. That's how I found my last one. People have parts lying around that they're not bothering to offer for sale, but will if someone comes looking.

    Otherwise yes, try to find one from an auto recycler, and yes, it needs to be an OBD2 harness.

    Try calling Zionsville Autosport (Indianapolis area) at 317-873-3216. They specialize in used BMW parts and know what they're talking about.

    Neil
    Awesome, thanks for the info!

  11. #36
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    I have a manual harness out of my 96 M3. Uncut and ready to go. I am in SoCal though so it'd have to be shipped. PM me if you're interested.

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  12. #37
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    I have a 99 M3 manual harness I can sell.

  13. #38
    NeilM is offline Member BMW E36 M3 Expert
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    ^^^^

    Hah! And there you have it.

    Neil

  14. #39
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    Quote Originally Posted by Braymond141 View Post
    I have a 99 M3 manual harness I can sell.
    Pm'd

  15. #40
    NeilM is offline Member BMW E36 M3 Expert
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    And one more thing for installing the replacement. Take a bunch of pix of the original harness before stripping it out. That'll help with the "does this bit go behind that other thing or in front" harness routing. I did mine a long time ago, before we all had great cameras in our phones, and that sure would have helped.

    Neil

  16. #41
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    Signing in to also say I have a 99 manual harness, looks like the OP should be sorted with the ones offered above but I'm posting up in-case anyone else who finds this thread is in need.

  17. #42
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    Quote Originally Posted by smr87 View Post
    Signing in to also say I have a 99 manual harness, looks like the OP should be sorted with the ones offered above but I'm posting up in-case anyone else who finds this thread is in need.
    Pm'd

  18. #43
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    Just an update on my wiring harness fail and a question. Firstly, I want to thank SMR87 here for reaching out and selling me his '99 wiring harness. Great communication and quick shipping, can't thank him enough. That leads me to my question though. My car is a 97 sedan 5spd. I got the old harness out, and have the new harness 50% installed, but have run into an issue.

    What is this connector on a 97 5spd? And why would a 99 wiring harness not have, or have a different, connector for it?

    missingconnection.jpg

    This would be standing in front of the car and looking down. I cannot for the life of me find a mate for this connector on the 99 harness. It's a dual flat-prong connection with red and yellow wires coming off of it. I would hate to be this close and not have the harnesses match up. Anyone out there know what I am missing? Thanks!

  19. #44
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    I think that might be the spot where the update harness for newer 12V crank sensor ties in. It’s a strange sub harness until you understand it. I have a vague recollection of using a 99 harness once that was updated and did not need the adapter sub harness but maybe I am confusing myself. Another possibility is that you have mixed something up with the vanos solenoid (which has a female end).

    There is no incompatibility issue. At worst you need an update crank subharness. Here is a lead to info that will help you understand the change:

    http://bavarian-board.com/uploads/kb...ion_Sensor.pdf

    Most cars have been updated since they are all 20+ years old and few original 5V crank sensors would have lasted that long.

  20. #45
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    Quote Originally Posted by pbonsalb View Post
    I think that might be the spot where the update harness for newer 12V crank sensor ties in. It’s a strange sub harness until you understand it. I have a vague recollection of using a 99 harness once that was updated and did not need the adapter sub harness but maybe I am confusing myself. Another possibility is that you have mixed something up with the vanos solenoid (which has a female end).

    There is no incompatibility issue. At worst you need an update crank subharness. Here is a lead to info that will help you understand the change:

    http://bavarian-board.com/uploads/kb...ion_Sensor.pdf

    Most cars have been updated since they are all 20+ years old and few original 5V crank sensors would have lasted that long.
    So this looks to be exactly what the issue is. So my next step should be getting a new 12v crank position sensor? I wouldn't need the new adapter though, correct? Since I've installed the 99 wiring harness that should already be wired for it?

  21. #46
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    I just checked, and my car definitely falls within the production date and chassis run of the recall listed in the PDF. So, just to be sure, all I would need to do is buy and install the updated 12v crank sensor and carry on, right? No need for the harness adapter since it's a 99 harness I've already installed. Just want to be sure before I move forward with the purchase. I have to get this done ASAP. Thanks!

  22. #47
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    Quote Originally Posted by pbonsalb View Post
    I think that might be the spot where the update harness for newer 12V crank sensor ties in. It’s a strange sub harness until you understand it. I have a vague recollection of using a 99 harness once that was updated and did not need the adapter sub harness but maybe I am confusing myself. Another possibility is that you have mixed something up with the vanos solenoid (which has a female end).

    There is no incompatibility issue. At worst you need an update crank subharness. Here is a lead to info that will help you understand the change:

    http://bavarian-board.com/uploads/kb...ion_Sensor.pdf

    Most cars have been updated since they are all 20+ years old and few original 5V crank sensors would have lasted that long.
    So after digging in this morning, I found my car already had that recall done, and the 12v crank sensor has already been installed, with the sub-harness installed as well. That's why the 99 harness I installed wasn't lining up with existing wiring, as 3 connectors were part of that sub-harness. I removed the sub-harness, installed the connector from the 99 harness directly into the crank position sensor, but it leaves me with nothing else making sense now. Does anyone know if a blown-up engine harness diagram is out there? This 99 harness plugging into a crank-position-recalled-97-engine with the sub-harness removed now is a mess and none of my previous labeling seems to add up.

  23. #48
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    Just wanted to say thanks to everyone who helped me out on this, as I got the harness completely installed and the car running last night (pic is not showing high idle lol, I was giving it some gas):

    20190526_202256.jpg

    I just wanted to follow-up with how it all got worked out in case someone searches this forum with the same issue, they can read this thread through til the end.

    My 1997 car had had the 12v Crank position recall done, which added a pigtail / sub-harness added to to the existing harness. This harness could *stay on the car* when removing your main harness and you might not even know it was there. It attaches to a bracket coming off the harness tray that runs along side the engine. I replaced my 97 harness with one from a 1999 car, which had a production date of 3/99. That's important, because by that date the engine harnesses had already been fitted for the 12v sensor and *you do not need the subharness at that point*. You'll know if your 99 harness doesn't need the subharness because it will have a wire with a half-rounded connection coming off that fits the CPS directly. It also makes a new connection that the 97-with-recall-done harness didn't have--that being the VANOS now connects directly to the last connector of the fuel rail:

    VANOS to fuel rail.jpg

    The connection hung me up for a while because it wasn't like that at disassembly. Otherwise, everything else lined back up. Also, I am just a schmo with some harbor freight tools and I did the job--So if you think it's too daunting, just go slowly, taking pictures and video of where everything goes in order as you do it...that way you can look through them in reverse to see how they go back...and you can do it. As others have said here, it can be done in a day, especially if there's no "oops there was a recall and now here's a subharness you never knew about" issue that pops up.

    Hope this helps someone in the future.

  24. #49
    NeilM is offline Member BMW E36 M3 Expert
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    Good job! Always nice to read a success story, and thanks for posting that useful CPS sub-harness info.

    Neil

  25. #50
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    Glad the harness worked out for you man!

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