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  • Alternator exciter wire mixup

    Hey all,

    I was replacing my alternator today with a new Bosch unit from turner. My previous battery was really old too so i replace that with a new one. After getting to the part where i hook up all the wires to the alternator, i had a momentary lapse and accidentally hooked up the 2 blue exciter wires to the positive large B+ lower stub along with the red large positive wire. So all 3 of those wires (2 blue and 1 red) were hooked up to that B+ pole. Ground was attached to the normal spot with the short 10mm bolt.

    Then i hooked the battery up and immediately, with the car off and no key inserted, i get a battery light on in the dash. So after realizing the error of my ways i reversed the wiring and put the 2 blue exciter wires in their proper location on the upper, smaller 'D+' pole.

    I have yet to start it yet because i fear i may have damaged something. Would i have damaged the voltage regulator of the alternator or something else with having the exciter wire incorrectly hooked up and powered on this way?

    thanks

  • #2
    I think you're Ok. The exciter wire is merely a 12V load (the bulb in the dash cluster) which causes the regulator to start putting out 13.9V. I believe the 12V from the battery back-fed thru the exciter wire and illuminated the light on the dash. I presume the light did not go on once you hooked the exciter wire to the proper lug? I'd say start it up.
    Ron ///Man

    • '91 Gr-A Former CiBiEmme / Ravaglia - Sold
    • '90 M3 Faux EVOII Alpineweiss 36K Orig Owner - The Queen
    • '91 M3 Faux EVO III Brilliantrot Euro Driveline - The Rocket
    • '91 M3 Faux Gr-A Club Racer DM - The Alter EGO
    • '89 M3 M3T / ITR Club Racer
    • '94 Spec E36 - Eh....
    • '09 M3 - Tarmac Terrorist
    • '04 330Xi Sport 6 Speed - Snowmobile
    • '07 530 Xi - Highway Star
    • http://www.imwcarparts.com/e30-m3-parts.htm


    Comment


    • #3
      Originally posted by Ron ///Man View Post
      I think you're Ok. The exciter wire is merely a 12V load (the bulb in the dash cluster) which causes the regulator to start putting out 13.9V. I believe the 12V from the battery back-fed thru the exciter wire and illuminated the light on the dash. I presume the light did not go on once you hooked the exciter wire to the proper lug? I'd say start it up.
      Agree with everything Ron said. I'd hook it up and start it.
      jimmy p.
      87 E30 M3 Prodrive British Touring Car
      88 E30 M3 Zinnoberot - Street
      88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
      92 E30 M Technic Cabrio - S14 POWERED!
      98 318Ti M44, Base - Morea Green
      04 Ford F350 - V10

      Comment


      • #4
        Thanks guys, hooked it up and it started up fine.

        Comment


        • #5
          Great to hear!!! Enjoy!
          Ron ///Man

          • '91 Gr-A Former CiBiEmme / Ravaglia - Sold
          • '90 M3 Faux EVOII Alpineweiss 36K Orig Owner - The Queen
          • '91 M3 Faux EVO III Brilliantrot Euro Driveline - The Rocket
          • '91 M3 Faux Gr-A Club Racer DM - The Alter EGO
          • '89 M3 M3T / ITR Club Racer
          • '94 Spec E36 - Eh....
          • '09 M3 - Tarmac Terrorist
          • '04 330Xi Sport 6 Speed - Snowmobile
          • '07 530 Xi - Highway Star
          • http://www.imwcarparts.com/e30-m3-parts.htm


          Comment


          • #6
            Hey, don't mean to hi-jack your thread, but since you already resolved it I am going to anyway :-)

            I need to replace the red wire on my alternator, as it is visibly cracked. Can anyone tell me what this wire is for? Does it run to the starter? I looked all over realoem, and can't find the wires connecting to the alternator in any diagram. Will I be able to replace it by just pulling the alternator, or will the intake manifold need to come out too? If anyone has a part # for it, I would greatly appreciate it too. I just bought BavRest's 4-wire ground kit, and when I saw this decided I wanted to wait to pull the alternator to do the alternator ground replacement until I have this wire too. Thanks!

            Comment


            • #7
              That wire is a part of the engine harness and is not available separately. I believe it is the alternator output which goes back to the battery junction connection on the firewall and also to the starter and a few other things that get power at all times. You are going to want to remove the plenum to access it. It's a big sucker, ETM says 10mm2 or 8 AWG.

              -chris


              ETM:
              http://www.bimmers.com/m3/troublesho...30%20M3%20ETM/

              some pictures of the harness out of the car:
              Alt connections and Oil Temp and Pressure sensors by chris tsay, on Flickr
              1988 M3
              2007 Lotus Exige S

              Comment


              • #8
                Damn, that is what I was afraid of! Thanks for posting.

                Comment


                • #9
                  I would get some red 3M Electrical tape from Home Depot and do a nice neat job
                  of re-insulating the wire. I've done this to several cars . I think it would be not so
                  easy to replace it.
                  Ron ///Man

                  • '91 Gr-A Former CiBiEmme / Ravaglia - Sold
                  • '90 M3 Faux EVOII Alpineweiss 36K Orig Owner - The Queen
                  • '91 M3 Faux EVO III Brilliantrot Euro Driveline - The Rocket
                  • '91 M3 Faux Gr-A Club Racer DM - The Alter EGO
                  • '89 M3 M3T / ITR Club Racer
                  • '94 Spec E36 - Eh....
                  • '09 M3 - Tarmac Terrorist
                  • '04 330Xi Sport 6 Speed - Snowmobile
                  • '07 530 Xi - Highway Star
                  • http://www.imwcarparts.com/e30-m3-parts.htm


                  Comment


                  • #10
                    Its no so bad to change it, cut the terminal off the alternator end and soft solder the new cable (just the end) to the new cable get a heat gun to make the sleeve baggy and gradually you can pull it through.

                    Comment

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