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running into electrical issues with our b35 swap...

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    running into electrical issues with our b35 swap...

    so, we have five days left until our m30 swap HAS to work. The transmission is not on yet, but that's a different story. We put the motor in, hooked it up regardless, and are attempting to make it work. Currently, the complete stock chassis harness is all gone, there is a custom harness controlling the C101 wires and sparse electrical things that have to be there, like the wipers, fuel pump, and pseudo-ignition switch.

    The main issue is that the motor cranks but does not have spark. Strangely, measuring current on the coil's posts seems to indicate that it should have spark, but yet no explodey is forthcoming. With the power in ignition-mode, coil sees 12v on black lead, when cranking it goes down to about 9.

    We've tried replacing the coil, no change was produced. My next suspect is the CPS which is on the front of a B35 motor, but I don't know how to diagnose it.

    ideas? thoughts?
    cars beep boop

    #2
    1. what is the year/model of the chassis?
    2. what is the year/model of the engine harness?
    3. cps can be "tested" with a dmm for impedence.
    Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



    OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

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      #3
      1. '86 e30, there's no chassis-side electronics so it doesn't make a huge difference...
      2. 01/89 M30B35 auto from a 635csi
      3. Any idea where I can look up that info? I'll look for a bentley at a book store but we are to the point where every wrenching minute counts.
      cars beep boop

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        #4
        our electronics guy looked through the harness diagrams and is now suspecting that there's a "i'm not being stolen" signal coming from the starter through the C101 that the ECU expects to be there in order to start. This is the Current Working Theory.
        cars beep boop

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          #5
          It all makes a difference :) Some had some kind of theft relay or something, my 84 did not but I still had to connect a green wire on c104? iirc under the dash for it to fire up on cranking.
          Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



          OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

          Comment


            #6
            Originally posted by Jean View Post
            It all makes a difference :).
            not when you don't have a fusebox or any stock wiring aside from a c101 pigtail and a windshield wiper pigtail ;)

            we stripped this car for srs
            cars beep boop

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              #7
              Originally posted by kronus View Post
              not when you don't have a fusebox or any stock wiring aside from a c101 pigtail and a windshield wiper pigtail ;)

              we stripped this car for srs
              Show me pictures of stripped car for srs and I will answer your questions
              ///Monstrosity. (OO≡≡[][]≡≡OO)

              Aside from showing yourself to be offensive, lacking experience and ignorant in the ways of business, you're also illiterate and imprudent. Beyond that, your sense of liability is severely impaired.

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