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    Main relay coil resistance spec.

    I just checked mine as part of a diag issue and found it to be between 3.4mega ohms and 9.15mega ohms depending on temperature. White, 5 pin, double 87.
    Can anyone confirm or deny. Is that normal?

    Thanks

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    sigpic

    #2
    I checked pins 85 and 86 btw.
    sigpic

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      #3
      Seeing the outside of any relay that nasty looking, I would pitch it immediately, even if it tested good.

      If there is that much hash on the outside, the contacts themselves would be toast.

      Closing SOON!
      "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

      Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

      Thanks for 10 years of fun!

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        #4
        I don't think I've ever checked a relay coil resistance, but that sounds way too high.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

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          #5
          As a general rule in a 12 volt system, anything with mega ohms in the circuit would qualify as an open. Relay is toast, get a new one, or a "new" one.

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            #6
            I kinda thought it seemed high. Just wanted to bounce it off you guys. Thanks a bunch, i will be ordering one here soon.
            sigpic

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              #7
              Originally posted by rares View Post
              I just checked mine as part of a diag issue and found it to be between 3.4mega ohms and 9.15mega ohms depending on temperature. White, 5 pin, double 87.
              Can anyone confirm or deny. Is that normal?

              Thanks
              That's really, really high.

              Are you sure you're reading mega (M), and not milli (m)?


              Leave Me Transaction Feedback

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                #8
                I have to say, the op's picture is pretty epic. .009 ohms (9 milliohms) would also mean the coil draws 1333 amps.

                current (I) = voltage (V) / resistance (R in ohms)
                Ma che cazzo state dicendo? :|

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                  #9
                  I've read some places it's roughly 70ohms across the coil.
                  '84 318i M10B18 147- Safari Beige
                  NA: 93whp/90ftlbs, MS2E w/ LC, 2-Step
                  Turbo: 221whp/214ftlbs, MS3x flex @ 17psi

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                    #10
                    70 - 80 ohms sounds right.
                    Ma che cazzo state dicendo? :|

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                      #11
                      hey guys, just wanted to update everyone on this so we can get thread closure for those maybe checking this later on. I went to the dealer and tested a brand new main relay. Because there are two diodes in there facing each other, the resistance is about 4-10k OHMS... that is normal... so if anyone is in need of that info... there it is

                      Resistance spec on 85-86 on the main relay of a late model e30 is 4-10kohms...

                      good luck everyone...
                      sigpic

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                        #12
                        So did you replace it and it works?
                        Ma che cazzo state dicendo? :|

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