no power to the ecu

Posted by KeelesKustome, Jan 8, 2011
Electrical Tech - Wiring, turbo timers, electronic boost controllers, gauges, fuses, wiring harnesses, wire tucks, car audio, and all other electrical component discussions.

  1. KeelesKustome

    KeelesKustome Proven Member

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    hey i need help

    my ecu is not recieving any power from pin 12 or 25, thus causing my car to not wana try to crank and the fuel pump not comming on.
    the relay in the dash behind the radio has been changed 3 times and it never makes any clicking noises.
    this relay also does not have a constant 12v going to it like i think it should even when the key is off.
    whats weird is when i probe the fuel pump wire at the ecu with my test light while having the key on acc, the pump will run until i let the probe off.
    i have messed with the neutral saftey switch with no luck.
    On my ecu pin it says the wire should be black,, this is not the case, it is black with a red stripe.
    I would like to try and bypass the N switch at the transmission as it is an automatic 2g, but i can not figure out the wire schematics on how to do so, and i am unsure if this would allow power to enter my ecu even if i did.
    I checked and bypassed the 20amp 30 amp and the 100amp fuses under the hood one at a time to make sure this was not my problem. it did not help.
    every now and then i'll here some clicking comming from where the neutral saftey switch is located.....
    I also changed the ignition switch with no luck. please help.

    i also locked and unlocked the car with the key to make sure it wasn't the saftey feature,

    i also ran a wire from the fuse panel with a constant 12v to the mfi relay where it says 30 amps, as this is suppose to stay charged and it doesn't, with my hard wire it does but has not fixed the problem and the relay still does not click or allow power to the ecu.

    i am considering the neutral saftey switch. :how do you get rid of this on an automatic that is staying automatic?

    ~~~~~~~~~~~
    ~~~~~~~~~~~~~~~~
    ~~~~~~~~~~~~~~~~~~~~~~~~~~
    i connected the neutral saftey wires, red with black stripe big, to the black big wire... nothing changed.

    i tried grounding the last mentioned wire, it already had ground and i added one, nothing changed,
    i ran from the 30 amp fuse power to the #12 and 25 pin the ecu starts up and shows the ecu light for 5 secs, so thats a sign the ecu is good i do believe. problem being the relay still isn't triggering the starter and the fuel pump..... why.....?

    also side note, now when the ecu is working so does my keychain to lock and unlock the doors, i checked to make sure it wasn't the security system again and it is not...
    please shoot me some more ideas to do, as i have swapped every othe mfi plug in the car where this one is and it isn't changing a thing, and i know they are good because i have tested them in other spots. the mfi plug seems to not be making it's ground properly,, where should i look for this at?


    ~~~~~~~~~~~~~~~~~~~~`
    ++++++++++++++++++++++++++

    okay so heres what i have done, the mfi relay: i added a ground to the side that wasn't getting it for some reason.... this allows the starter to now crank over.
    although the ecu light isn't comming on because it's still not getting power.
    so i add the 30 amp fuse direct path power wire to one of the terminals, i think 25, noww the fuel pump kicks on and it turns over and the cel light comes on for 5 seconds,
    I am here by myself so checking for spark is hard, i manage, and i have none.
    I can only assume that the relay is messing that up too... i think what the heck is going on with this?

    i have swapped this relay numerous times and still nothing,, and how come i am not getting fire even bypassing it.?


    :cry:

    some info i might try that i found.(


    Originally Posted by Turblown
    Here is the short version of what it says to check for the relay.

    Section 4-3, Fuel Injection Control Relay Check. (just the relay)
    This tests the MPI side of the MPI relay
    step 32 - Remove EFI relay
    step 33 - Connect battery positive (+) to terminal 10 and battery negative (-) to terminal 8
    This should activate the one side of the relay causing it to connect pin 10 to pin 4 and 5
    step 34 - Connect voltmeter negative probe to the battery negative terminal, Connect voltmeter positive probe to terminal 4 and then to terminal 5, There should be 12volts at each terminal.
    if you do this before step 22 you'll see pin 4 and 5 don't have 12v before hand and do after

    This tests the fuel pump side of the MPI relay
    step 35 - Connect battery positive (+) to terminal 9 and battery negative (-) to terminal 6
    step 36 - Check for continuity between terminals 2 and 3, there should be continuity, next remove the ground lead from terminal 6 and check again, there should be no continuity.
    step 37 - Connect battery positive (+) to terminal 3 and battery negative (-) to terminal 7
    step 38 - Check for voltage between terminal 2 and the battery ground, there should be 12v
    step 39 - If the test results are incorrect, replace relay with new part.

    According to this my relay passed, but maybe not.

    What this doesn't test is that MPI relay is functioning in the car. For that you need to check that you have 12v at the connector for pin 10 all the time, turn on the ignition switch and verify you have 12v at pins 4 and 5 when the ignition switch is in the run or start position.
    If the the relay checked out but you done see 12v at 4 and 5 then you need to look at the ECU and the signals going to it. )
     
    Last edited: Apr 6, 2011
    #1
  2. KeelesKustome

    KeelesKustome Proven Member

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    alrighty: no responses still ehh. who wants to help burn my car? :ohdamn::beatentodeath:

    what can i say? syptoms have slighty changed.

    tonight i put the original relay back in, i have added a ground to the side that doesn't seem to want to ground on it's own, and the car will turn over like none other. but still no fuel pimp or ecu light..
    so i put my hard wired power wire to pin 25, the fuel pump and ecu light do their thing, i checked to see if pin 4 &5 get power when i turn the key and they do,, it's delayyed and blinks like it's surging the power or something.
    although
    pin 10 ignition power transitor( a to coil for cyl 1&4) , pin 38 mfi relay power supply
    pin 71 ignition switch, pin82 ignition switch 1g all do not recieve any power with how i have it setup with the hard wired power wire,


    so i know i still have problems but i don't understand where? whats also interesting is with this setup i plugged in my dsmlink and it works, it allowed me to manipulate all the functions normally.. this blew me away, as i didn't expect it to work.
    something odd as well is the neutral saftey switch on the tranny keeps randomly making a clicking sound, sometimes it's a short burst of sound, other times it is a long click sound.


    correct me if i am wrong but the neutral saftey switch would keep it from turning over right?
    if so is this why i have to add a ground to the relay for it to turn over?

    but would that keep the ecu from seeing power?

    or is it causing the mfi relay to not ground thus not sending power to the ecu as well? :sosad::sosad:
     
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  3. sniver

    sniver Proven Member

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    I'm posting so ill remeber to read your pposts and properly reply in detail later. First thought at a glance is the ecu is damaged. The circuit that pulls the mpi to ground and acitaves it. Mines done that before.



    Sent from my Droid
     
    #3
  4. 1990AWD

    1990AWD Supporting VIP

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    try PMing Steve. he'll know.
     
    #4
  5. sniver

    sniver Proven Member

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    This is my interpretation of the fsm and my experienced with 1gs. I know yours is a 2g, but its all relevant

    The ecu should receive power on pin 25 and 12 from the mpi when pin 38 on the ecu is pulled to ground. And the fuel pump is kicked on when pin 8 of the ecu is pulled to ground.

    pin 38 is pulled to ground anytime that the ecu gets a power from the ignition wire, at pin 82.
    pin 8 is pulled to ground under certain conditions when the ignition provides power to pin 82.

    With key on check for power at pin 82. If you have power there , attempt to provide grounds for pins 8 & 38 to bypass the ecus mpi control and force it on. By grounding those two pins, you should have power to the fuel pump and pins 12&25.

    Make sure there is continuity between pin 38 and pin 8 of the ecu with there respective mpi terminals. I would say which, but the pin numbering for the mpi on the fsm is illegible.


    Pin 71 is the ecu signal for the key in the start position. should only have voltage when turned to start, fsm says over 8volts is acceptable.. If it doesn't have power in the start position you"ll have to: check continuity between pin for the ecu and pin 4 for the starter relay. then verify that the relay works, make sure pin 4 has continuity with pin 5 when pin 1 is connected to power and pin 3 is connected to ground. then check continuity between pin 1 for the starter relay and pin 9 on connector B-63. If the cause for no power to pin 71 is not found by this point theres an issue with the theft deterrent system.

    You said you have no spark, but do you know if you have injector pulse?
    Do you have power to the coils? I can explain how to determine if needed.
    All the while your not throwing any codes?

    *edit. I found a discrepancy in my manuals. The electrical manual says pin 82 for Ig1 voltage input, and the body/motor book says pin 92...though its in a list between 81 and 83. mistype perhaps?
     
    #5
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  6. KeelesKustome

    KeelesKustome Proven Member

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    I'm gona try in order what you have written.

    as for the previous comment about the ecu being bad. i don't believe that it would allow me to hook my dsmlink up if it were bad, also woundering if my 1g engine swap cas may be turned out 180. causing the no fire.

    either way i need my ecu to see power , other than being jumped form a positive 30 amp fuse.

    to the previous post, you don't recon my neutral saftey switch could cause all this do ya?
    also when the ecu is powered up my key chain lock , panic etc... work and their is no blinking red light on my car, and in my history that tells me the security is fine. whats your opinion?
     
    #6
  7. sniver

    sniver Proven Member

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    I'm not really familiar enough to comment on the security system. If you can unlock it, it should be fine.

    The circuit for the mpi activation has nothing to do with communications. Ecu might still need replaced.

    The neurtal safety switch just disables the starter relay, if you bypassed it, it would still run.

    Sent from my Droid
     
    #7
  8. KeelesKustome

    KeelesKustome Proven Member

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    okay.... hmm.
    so the relay sends power to the ecu which in turn sends power back and forth telling everything to work correctly..
    soooo i need to remove my bypassed ground on the relay and check what you have mentioned. I'm just thinking why am i having to bypass the groud on the relay to get it to turn over?

    would that mean my relay is for sure bad?
    either way i just ordered a new one from MIt's dealer, and it'll be here thursday.

    the ecu being bad: I baught it for nearly $400 from Twenty5psi on here, and he swears up one side and down the other it worked/ran etc.. and has witnesses of this. I tend to believe him as well.
    I opened the box and it has no smell and no burnt spots.

    here is a random thing, 2 yrs ago my dogs ripped my bumper off and ripped up my wiring harness on the passenger front side, around 9 wires were damaged, but most were still together, i fixed them the proper way, whats the chances one of the 5 black wires may have got crossed causing this? as their are alot of identical solid black wires with silver dots. i measured the distance of the dots and made sure when re-applying solder that the wires were indeed dot spaced correctly to identify the wires... needless to say i am 99.9% sure this isn't my issue just a side note.

    also: i don't think i had bypassed the n saftey switch correctly. as it's an auto and their seems to be some confusion in the dsm world to do so.
     
    Last edited by a moderator: Jul 10, 2014
    #8
  9. sniver

    sniver Proven Member

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    To clear up confusion, there is no neutral safety switch on an automatic. There is an park/neutral position switch, it reads the gear lever location.

    <a href="http://picasaweb.google.com/lh/photo/nCQd_iWRapSZmltWhJ-3kaqsuFuYsrgaTTk9Q9-cPQc?feat=embedwebsite"><img src="http://lh4.ggpht.com/_Ziaf2eJ7svA/TSvZc1fNfdI/AAAAAAAAApQ/7hm2lXJ_DXU/s640/98dsmstartcircuittheft.JPG" height="640" width="474" /></a>

    ignition start > theft relay > starter relay> park/neutral position switch> ecu.

    ecu provides a ground path for the 12v, thus energizing the starter relay, if and only if the etacs ecu(theft deterrent) has already energized the theft relay for the voltage to pass through.

    I don"t know how well you can read schematics, but this should help if you can.
     
    #9
  10. Absit

    Absit Proven Member

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    I couldn't even begin to read your post. Colors, bold, tildes everywhere. Type a proper paragraph if you want a proper response.
     
    #10
  11. sniver

    sniver Proven Member

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    HAHAHAH I read it all via my phone so it wasn't gaytarded. I agree :D

    Next Ill just start replying in ninja type.

    Then I'll just hide it in the shadows to never ever ever be seen again LOL.
     
    #11
  12. KeelesKustome

    KeelesKustome Proven Member

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    sorry the colors are for evertime i add something, so it can be seen what has been automerged.
    sorry i wasted your time.

    BTW: you add to this thread was neither helpfull or worth my time.
    (good thing you didn't mention spelling, that would have been really oxymoronic) I get sick of going through threads where people need help and find resposes like that.
     
    Last edited: Jan 11, 2011
    #12
  13. sniver

    sniver Proven Member

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    Don't fret the little stuff, just use bolder colors. The only one I can't stand is the salmon color, its all white text on black when I read it off my phone so it ain't a big deal.

    What I want to know is where in that schematic you had to jump to ground to make work.



    Sent from my Droid
     
    #13
  14. KeelesKustome

    KeelesKustome Proven Member

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    okay,
    we have searched and followed and found that my alarm system isn't recieving power, inturn it's the fuel pump relay is not getting power because the ecu is not getting power and the starter relay is not getting a constant 12v either.

    the ignition switch is giving the power it is suppose to with the key to acc and all the way forward...... we are verry lost now.

    what the heck....

    also their is a ground on the passenger side of the center compartment, near the mfi and fuel pump relay, it looks factory and it is cut. any ideas where this wire is suppose to go? it's all by it'sself bolted to the metal frame of the dash.
     
    #14
  15. sniver

    sniver Proven Member

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    Ground wire near the ecu just gets grounded to a bolt near the ecu.

    I'm looking into the theft system problem.



    Theres a lot of fused inputs. Verify again to ensure your not making a simple mistake.


    [​IMG]
    Ignore the J/B#11 fuse here thats thh blower, oops. The dedicated #11 fuse is in the engine bay.
    [​IMG]
     
    #15
  16. KeelesKustome

    KeelesKustome Proven Member

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    your diahgram isn't the correct one for my automatic with an alarm system, the relay for the alarm is up under the dash not near your kick panel, and it's the top left square relay, with the same schematics as the starter relay behind the radio,

    the ignition is sending power out, but as you can see in this diagram even though it's not the best, we have an Alldata one we have been using and it shows that the antitheft should recieve power at the same time the ecu sends power to the mfi while alsoeving power to the starter and fuel pump relay.

    none of this is occuring at all,

    we tried adding a 12v directly to the antitheft fuse where the 12v constant should be, but it changed nothing... meaning that the power still isn't making it past the ignition transitor box or something..
    i tested it and all of them seemd to be grounds, which i thought was interesting, as it has a blue and red wire going to it, which is the same color as the power back up supply for the ecu... now why would that be going to the transitor ground box on the firewall?

    [​IMG]
    i colored it if you can see.

    i have deleted my cruise system, but the fact remains that my starter still isn't even getting something to try to crank. when the key is turned to on it gets power, but the relay isn't switching for the ground to engage because the ecu isn't getting power to tell it too.. i have a short in a narrow area, but i cannot find it, and i don't understand why i would in the first place as none of this has been touched in the time it has been blown up.,, i really hope your right and i am over complicating it. at this point i am either going to buy a new wiring harness and see if that fixes it or part the car out and cut my losses.
     
    #16
  17. sniver

    sniver Proven Member

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    Which diagram isn't right?

    Yours says b-57 is the starter relay, mine does to...for a 2.4 m/t car.

    Yours is a 2.0 turbo auto, right???

    Where don't you have power at the etacs, described by connector#,pin, and color preferablly

    After we sort out out connect differences... Go through this. tell me where the 12v ceases to exist. I Imagine you wont have 12v after b-44x pin4. Verify this please.

    battery
    sub-fusible #6 30A
    b-78 pin 1
    b-09 pin 1 (ignition switch plug)
    b-09 pin 5 -------(with key in start position from here forward)
    B-44x pin 4 (theft relay)
    B-44x pin 3 (theft relay)
    ---------------------------
    If you don't have 12v at B-44x pin 3, see if there is power at B-44x pin 2.
    ----------------------------
    B-63 pin 9
    B-96 pin 1 (starter relay)
    B-96 pin3 (starter relay)
    A-101 pin 8 (inhibitor switch)
    A-101 pin 7 (inhibitor switch)
    ----------------------------
    B-96 pin 5 (Starter relay)
    B-96 pin 4 (stater relay)
    A-34 pin2 (engine harness to starter harness)
    A-35 pin1 (on starter solenoid)



    Edit:
    This is from the factory service manual, not alldata. For a 2.0 turbo 97-99 eclipse.
    [​IMG]

    Edit: It doesn't appear that the etacs theft ecu can do anything other than interrupt power to the starter. It doesn't look like it has the ability to affect ecu power,mpi power or any of the sort.

    If you were to jump B-44x pin 4 to pin 3 that seems to me as if it would complete bypass the theft system. Thoughts, opinons?
     
    #17
  18. KeelesKustome

    KeelesKustome Proven Member

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    I'm pretty positive that the car is designed where jumping the antitheft is slim to none.
    although i do see what your saying, and my mechanic who's been helping just remembered he has a tool he baught and hasn't ever used that goes on wires and fuses and tells if the signal is interupted or broke somewhere, this may be my salvation, because for the last month it's been hit or miss trying to work on it and i'm mentally drained and i'm ready to throw in the towel.

    edit: the starter relay is getting power, it's not switching the ground over to crank, i am unsure if bypassing the antitheft would even help that.
    also why does it have so much about the cruise controll on here...>? i deleted mine this go around, do you recon that might have anything to do with it.
     
    #18
  19. sniver

    sniver Proven Member

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    That tool is either a continuity test, or a multimeter on ohms.
    Ignore the cruise crap, it makes no difference.
    If the starter relay getting power, then its not a theft system problem. its after the theft system.

    Just do that test I asked, completly, and I can proceed from there. Were jumping around system not verifing much. I still think its a ground or the ecu.
     
    #19
  20. KeelesKustome

    KeelesKustome Proven Member

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    i will, i brought the ecu home to inspect it again and take photos. the fellow at ecmlink doesn't think it's my ecu just because it's not getting any power to it, and when i do give it power, all the functions work properly.
     
    #20
  21. sniver

    sniver Proven Member

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    I know for a fact the mpi circuit can fail. It will will not ground the mpi, and not powering the ecu. You can bypass the mpi power and it will work normally. Been there, seen that. New ecu and we were good to go.

    I need to refresh myself, I go through so many threads I can't remember what sh** we've gone over LOL.
     
    #21
  22. KeelesKustome

    KeelesKustome Proven Member

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    true, but a little refresh:
    the wires going to the ecu aren't even recieving power. so it's something before the ecu that would seem to be causing the issue.

    I like that your actually trying to help: ALOT!

    Thankyou

    :)mad:I get tired of everyone saying it's your ecu, your relay etc... thinking your a bank who can keep throwing money at stuff that you can't afford in the first place, only for it to not fix the actual problem. And then be told ohh your new part was probly bad... ~~seriuosly~~ come on.....:beatentodeath:

    and all 300 threads i have found with the similar issues i am having never get resolved or the owner never comes back and tells us the reslove, and i send emails on emails requesting info with no responses, :banghead: and sit in a chair and read for hrs at a time only to conclude with no resolve... by gosh darn it mine will be resolved and i will post up absolutely everything i did to remedy the situation, so someone in the future can actually have a freakin diagram on what to do and check for----I'm done venting now....I'm just angry at the situation :ohdamn: )

    edit: heres a kicker.......... aldata shows another fuse panel on the passenger kick panel, that has a second antitheft relay..... wow, this may be the b44x you were mentioning........... interesting.....
    this car has more wiring than the new electric cars.... and i'm serious. those are easier to perform tests on than this spaghetti of a mess.

    alrighty here they are.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    #22
  23. sniver

    sniver Proven Member

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    Okay back to basics.

    The car should crank without a ecu in the car. Does it?



    The ecu should receive power at pin 82 with ignition on. even w/ no mip relay installed
    Make sure you have ground at pin 26 also.
    -------------------------------------
    http://www.dsmtuners.com/forums/articles-tuning-ecu/281763-2g-turbo-ecu-pinout-w-wire-colors.html
    -------------------------------------
    http://www.dsmtuners.com/forums/articles-tuning-ecu/246467-how-identify-ecu-pin-numbers.html
    -------------------------------------

    Edit:

    Can you make it run? if so how?


    I want to know
    0. Does it crank?
    1. voltage at ecu's 82 with key on
    2. ohms to ground from ecu's pin 26
    3. If you made it run once, what exactly did you do. \/ \/

    So it will run the car when the power is manually provided?
    -----------------------
    Edit:

    4.
    [​IMG]

    So the relay gets voltage to terminal 1 & 5 ? This means the theft system is not disabling the car. The theft disable relay is before that.

    So its not switching it to ground.

    pin 3 should have less than 1 ohm to ground in park and nuetral, and out of limit (open) in anything else (d,r,ect...)

    pin 4 goes to the starer solenoid. you need to check to see if there is about an ohm there to, between pin 4 of the starter relay (b-96) and the activation wire on hte start solenoid(a-35)
     
    Last edited: Jan 31, 2011
    #23
  24. KeelesKustome

    KeelesKustome Proven Member

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    gotcha, i am going to print this out and do it in order to have an acurate reply, instead of frustration when i get home.
    when this is resolved you will be getting a helpfull link added :thumb:
     
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  25. sniver

    sniver Proven Member

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    Was that a threat? :cry:

    Solve it or no cookies for you! ROFLROFLROFL

    It will get solved. There is a finite amount of sh!t to sift through. As long as you don't report any misinformation! :p
     
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