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Main relays not clicking after swap - no start - any help?

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    #1

    Main relays not clicking after swap - no start - any help?

    So I wired up the car - confirmed it all today. Buttoned it all back up etc and went to crank. Starter turns, motor turns, but no fire. Ok. I went over and felt the couple relays on there and nothing clicks when the key is on or when the starter turns. I stock my volt meter in the pins and what I think is the main relay does not get any +12v over the little green wire when the key is on. Is this right? I don't think it is.

    Any help is appreciated - not sure where to start but I don't hear the fuel pump or any relays in for the fuel/main click.

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    #2
    Did you wire a CEL? That's the easiest way to see that the ecu is alive. When you switch the ignition on, the main relay should click, sometimes the fuel pump one too but not always (not sure how it decides, maybe just a timer).

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      #3
      Sounds just like the problem i had. Who did your wiring? You or did you have an adapter made? Pm me and i can tell you what i did to fix mine and i can send you a copy of my pinout
      Originally posted by NitroRustlerDriver
      I don silk gloves and place them into a sacred envelope made of magic and lined with Unicorn fur, seal the envelope with an adhesive made from strands of Gypsy hair and wrap the whole thing in a snazzy looking faux gold leaf paper, with elm leaf inlay from Costco. Unfortunately, by the time it gets to you, all of that fancy stuff will likely have been picked clean by the greedy postal service employees. Please don't be surprised to see just a plain envelope.

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        #4
        I did my wiring. This is on a 1987 year model 325e, build date 8/86 I believe.

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          #5
          Ok so... I think I might be onto something. Doh!

          What I did was use an M50TU harness that I had bought of ebay (so not sure of the year) that was listed as an E34 one. Seems to be. Then, I cut off the X20 connector on that harness about 4" after the connector and cut the C101 connector about the same off of the M20 original harness. Hooked it up, no fires, car cranked (when jumped, battery shows 9 - 10v now... totally dead) but no start. My timing light didn't trigger either. Damnit.

          So then I started looking at how the ECU gets power to determine whether or not it was getting power. Pin 56 on the 88-pin DME connector is +12VDC from the ignition switch (terminal 15). So you turn the key, the ignition switch spits out voltage that turns the ECU on. The ECU then controls the main relay via pin 27 and the fuel pump relay via pin 1.

          Well... I put my volt meter on pin 56 and turned the key - nothing. No voltage present. Well, if the ECU doesn't turn on, then it sure as hell isn't going to turn the pump/main relay on. So I traced pin 56 which is a smaller green wire. I remember tapping this wire on my E34 to control my main relay and such with the key on. So I traced this wire and was pretty sure it was supposed to hook to pin 7 on the C101. It seems to - in fact, the coils get power so that means the ignition switch is working and pin 7 is happy... but no ECU power.

          Then I realize...



          So on the left is the X20 connector I chopped off the harness that is in the car now. On the right is an X20 from a bad harness I have (no, I didn't make it bad, it was delivered to me that way).

          So you can see the small green wire crimped in the large gauge wires coming from Pin 21. One X20 has it, one doesn't. The one that has it, I screwed up and cut behind the crimp. Doh! So, my little green wire is likely laying down in the harness area all taped up/heatshrinked up so not to short... when in fact it should be hooked to this junction. Poopy!

          Comment

            #6
            the things you can do when you understand your car. Great job working this out on your own. Hope this is your fix. There is always something on a swap.

            Originally posted by Roysneon
            $5 shipped?
            Originally posted by MarkD
            You are a strange dude, I'n not answering any more posts from you.

            Comment

              #7
              I don't want to jinx it, so I don't want to say it, but this hasn't been too bad granted it doesn't run yet lol. I haven't rewired that green wire yet. It would be less confusing if there weren't so many posts on the internet that weren't exactly correct!

              That said, here's my "other" project lol



              Makes the E30 wiring look like mickey mouse stuff haha

              Comment

                #8
                Damn that splice! Same thing happened to me when I did my swap. I even had deja vu reading your "realization" post. Add that second green wire and you'll be a happy man!

                Sent from my DROIDX using Tapatalk

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