M42 power connections and ground

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  • jaredmac11
    Wrencher
    • Sep 2007
    • 253

    #1

    M42 power connections and ground

    Could someone help me identify these connections? I think one grounds to the strut tower, the other possibly to the power distribution box (???) and the final one... not sure. I thought batteries were mostly in the back for the 318is so Im not sure why there is a positive terminal. It looks new so Im thinking maybe it was left alone? Maybe wrapped?

    Also, does the M42 ground to the block at any location? I know there is the ground cable from the passenger side engine mount.. does a ground go right to the block?
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  • Ebenezer
    Member
    • Aug 2016
    • 61

    #2
    In terms of a ground going to the block, there should be a ground wire going to the oil pan IIRC. Not exactly to the block, but it's at the bottom of the motor. I remember looking at realOEM and seeing there was supposed to be a ground wire going from the motor to the body. My car is missing this wire though, probably thanks to the PO.

    Sent from my SM-G930P using Tapatalk

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    • jaredmac11
      Wrencher
      • Sep 2007
      • 253

      #3
      Is that the alt ground?

      For the negative terminal on the battery, is that ran up from the rear and grounded to the block, or is it grounded inside the trunk?

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      • Ebenezer
        Member
        • Aug 2016
        • 61

        #4
        Originally posted by jaredmac11
        Is that the alt ground?

        For the negative terminal on the battery, is that ran up from the rear and grounded to the block, or is it grounded inside the trunk?
        I don't think it's an alternator ground, but I can't say for sure.

        The negative terminal on the battery should be connected to the body in the battery compartment. The cable is less than a foot long.

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        • Ebenezer
          Member
          • Aug 2016
          • 61

          #5
          Originally posted by Ebenezer
          I don't think it's an alternator ground, but I can't say for sure.

          The negative terminal on the battery should be connected to the body in the battery compartment. The cable is less than a foot long.

          Sent from my SM-G930P using Tapatalk
          I'll need to take a look tomorrow and see where the alternator ground goes

          Sent from my SM-G930P using Tapatalk

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          • e30sh
            Mod Crazy
            • Apr 2015
            • 618

            #6
            Main ground goes from engine arm to the lug on the frame rail. Other ground is shown in your hand..it grounds to threaded insert in front battery tray. The battery termanal and the other lead above your hand are hot and are attached to the + wire junction block.

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            • jaredmac11
              Wrencher
              • Sep 2007
              • 253

              #7
              Originally posted by e30sh
              Main ground goes from engine arm to the lug on the frame rail. Other ground is shown in your hand..it grounds to threaded insert in front battery tray. The battery termanal and the other lead above your hand are hot and are attached to the + wire junction block.
              Ah-ha thank you!. I didnt think there was actually a terminal in the E30 engine bay... that makes sense... Man, this would have been 100x easier if we had e30's in our junk yards so I could have just taken their wiring set ups.

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              • e30sh
                Mod Crazy
                • Apr 2015
                • 618

                #8
                This shows the harness ground. The + block is right behind the cover on the firewall.

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