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ECMlink Bonehead mistake, hoping for the best, Please help...

Posted by Sbgriffin, Feb 19, 2019

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  1. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    So this one I'm ashamed I'm having to ask about, completely preventable, and I know better. So I was installing my new aem uego wideband, putting the sensor in place of the stock o2, and so I could log with link. All was going peachy til the last step, tapping into the O2 signal input at the ecu. I looked up several pinout diagrams, thought I knew exactly where to go. Well turns out there's a second white wire directly below, for the CPS. And in doing my soldering, I had pulled that harness down, and apparently was looking at it backwards. After one short crank I knew it wasn't correct, backtracked and found what I did. Also confirmed through DTC on link. So I quickly fixed my mistake, soldering and heat shrinking. Then tapping into the right wire. But unfortunately I'm still getting the same DTC, crankshaft position malfunction. So I'm afraid I may have damaged the ECU? Also I already tested with a ohm meter to make sure I had continuity on the white CPS wire, it's good. Any help would be greatly appreciated, I'm starting to freak out here.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  2. lglracer

    lglracer Supporting VIP

    77
    14
    Joined Jul 13, 2008
    Sacramento, California
    Both should be a 5v signal so you should be fine. DSMlink - I would verify that the crank position sensor is reading correctly and try to clear the CEL. You may have flooded the engine with it reading a positive voltage the whole time. Double check your wiring. Another way to check the Crank position sensor is to pull the wires and plug to see if you still have spark. If you have spark the engine is getting the correct signal. If not check the ignition system to make sure nothing fried being on for so long.
     

    Road Race Build 450  1

    1991 Mitsubishi Eclipse GSX
    manual · 1G DSM

    Street Build 408  1

    1990 Mitsubishi Galant GSX
    awd · manual · Galant VR-4

    Street Build 1K  4

    1991 Mitsubishi Galant VR-4
    awd · manual · Galant VR-4

    461  0

    1991 Mitsubishi Eclipse N/T
    manual · 1G DSM
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  3. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Good point, I'll check for spark tomorrow. I did however clear the code twice. It came right back the first time, 2nd time it didn't. Probably because I didn't crank it over anymore. But that makes me feel a little better, being there both 5v inputs. Can't really see how that would damage the ECU, especially how little it was powered up. Guess we'll see, fingers crossed. Thanks.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  4. SasaniFab

    SasaniFab Freelancer

    2,152
    590
    Joined Dec 1, 2013
    danbury, Connecticut
    Did you clear the codes? You may just be registering whats in the memory
     

    Street Build 3K  20

    1992 Eagle Talon TSi
    645 whp · 498 lb/ft · 1G DSM
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  5. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Yeah so I've cleared the code several times now, it keeps on coming back?. I just got done retracing my wiring, and I'm confident it hooked up right now. I also unhooked my cam position sensor plug, using a scrap piece of wire, and an ohm meter I tested continuity. From the ECU to the cps, it's all good.
    So what should I test now, is there a fuse it could have popped? Starting to get a little concerned about the health of the ECU? Any input would be great, thanks again.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  6. ThunderChild

    ThunderChild Supporting VIP

    2,541
    713
    Joined Jan 5, 2012
    Rathdrum, Idaho
    I did the same thing when I hooked up my mtxl wideband, but once I rewired it correctly all was good. I'd really go over that wiring again, I actually ran my car for a little bit and it was misfiring like crazy, then I realized my mistake and fixed it. Maybe double check your solders, you can get continuity through one strand of copper but still have a bad connection for voltage or signal.
     

    Street Build 218  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    316  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 868  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 1K  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  7. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Yeah good call, i'Il look it over again tomorrow. If that doesn't work out, I guess I need to test the cps circuit. That shouldn't be too hard. Got a switched +12v, ground, and white signal wire. Not sure, but I think the forth wire is for tach signal?
    Either way I'm sure I'm just missing something here. The lesson to be learned, always double check your wiring:banghead:. Especially at the ECU. Ill keep you posted, thanks.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  8. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    So I just had a thought, might simplify diagnosing this. So I do have a second ecu, non-eprom. But I could hook it up, just to see if it fires. Obviously it wouldn't be scaled for my injectors, or anything else. So I wouldn't run it long. But does anyone see any issues with that plan?
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  9. motomattx

    motomattx Proven Member

    1,759
    557
    Joined Dec 9, 2010
    wampum, Pennsylvania
    Try it, shouldnt hurt anything as long as you fixed the problem.
     

    Drag Race Build 3K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  10. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    After more testing today, there's good, bad, and more confusion. The first thing I did was remove the ECU, and triple check all my connections. I'm 100% confident it's correct now. Second I plugged the ECU back in, and tested all four wires with my multimeter at the CAS. Looking at the picture below, here's what I have. The white and yellow have a +5v, the red is 12v, and blue is supposed to be my ground. But the thing is I can't get a ground source from it, like it has a open circuit. Also I'm kinda confused about the white wire, I thought it was supposed to be the input back to ecu? But it seems to have a constant 5v?
    So after testing all of that I decided to throw my stock, non-eprom ecu in. Just to see if it would fire, but nothing, same issue. Next I repeated all of my voltage tests at CAS, with that ECU. And all was exactly the same, so I'm guessing the ECU isn't the issue. So I'm guessing I have one of two things going on. A bad ground for the CAS circuit, or a bad CAS?. Not really sure how my ground would bad, I didn't disturb any of that. Anyone have any ideas, I'm kinda baffled here? Thanks again.
    20190221_164339.jpg
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  11. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    So if it's an open ground, should I just supply a new one to the ECU? If so which pin is right ground for the CAS?
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  12. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Alright I can definitely use some input on this. Ive pretty much confirmed that I have a bad ground at the CAS, it's the only wire I can't get an ohm reading through. I'm testing each wires resistance individually, from the ECU, to the cas plug. So the only explanation I can think of is, I might have snagged a wire when I was drilling a hole through the firewall?. I really don't think so, I was pretty careful, but it's possible. Is there maybe something I'm not seeing correct here? I'm pretty sure pin 4 on the cas plug should be one of the sensor grounds at the ECU? Any input would be greatly appreciated, I'm kinda stuck here. Thanks.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  13. motomattx

    motomattx Proven Member

    1,759
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    Joined Dec 9, 2010
    wampum, Pennsylvania
    Run a temporary ground for it and see if anything changes.
     

    Drag Race Build 3K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  14. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    So after running a temp ground from the back of the intake, to the cas plug pin 4. The car fired right up, just like normal. Huge relief:thumb:.
    But now I'm wondering what I should do for a permanent fix?. Obviously it would be nice to know what exactly caused this BS. If I did happen to have snagged a wire drilling through the firewall, I'm sure there's more collateral damage to other wires. But it's really not that easy of a job to investigate the harness behind the dash. I did however test every single wire from the ECU with an ohm meter, making sure no wires have crossed paths. So I think it's safe?. One more question, shouldn't I ideally ground that back to the ECU, to the same pin it should be on? If so, which pin is right for the cas ground? Any idea, or does it even matter where I ground? Thanks again.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  15. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Also a heater core job is in my future, I'm starting to smell antifreeze. So maybe I can do a temp fix for now, and thorough investigation/fix while I'm in there?. Does sound reasonable?
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  16. motomattx

    motomattx Proven Member

    1,759
    557
    Joined Dec 9, 2010
    wampum, Pennsylvania
    The grounds for the sensors in the ecu are tied together internally, grab any of the sensor ground inputs and use that, I dont know that I would bother looking forever for what got damaged unless your bored and just really want to know, I would run a good new ground and call it a day, figure a fresh ground is likely better than the 20 year old wire thats in there now anyway.
     

    Drag Race Build 3K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  17. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Good to know, that's where all go with it then. For all I know it could just be my degrading harness anyway. Wouldn't be the first point of failure on it. Been slowly replacing one plug after the next. Anyway thanks for the help.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  18. nopistons93

    nopistons93 Probationary Member

    20
    8
    Joined Sep 26, 2014
    Monterey, California
    • If all your other wires readings are SAT I'd say you have no issue with them. Totally normal to fully rely on the resistance readings for wire continuity in areas where physical inspection is tedious or impossible without tearing down the machine. I'd feel like you though, I'd want to know what's causing the ground since it's not the ecu (as you proved with your spare).
     

    523  4

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  19. Sbgriffin

    Sbgriffin Proven Member

    165
    12
    Joined Jun 14, 2017
    Lewiston, Idaho
    Yeah I agree, I've been loosing sleep over it, trying to figure out what happened. But I figure it's time to move forward, and do a sanitary fix, supplying a new ground. Then here in a few months I'll be doing a heater core replacement. I'll be able to thoroughly inspected back there, and possibly fix any damage. Thanks for the input.
     

    Street Build 841  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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