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    #1

    Battery Light is ON but...

    Two days ago, I started the car up to go to work and the battery light stayed on. I figured this meant the alternator wasn't charging properly and I tested the system voltage with the car running and all accessories off.

    I got 13.5 volts IIRC. That seems as it should be.

    I know the alternator is old, so I figured maybe it was starting to become borderline and I took it out to a local shop that does starters/alternators and had them test it. He said it tested exactly as it should.

    I put it back in the car and the battery light is still on. It's brightness seems to increase with RPM up to about 1500 when it is fully bright.

    I've driven the car around since then and the battery doesn't seem to be losing power.

    So can anyone tell me why the battery light is on? It bothers me!

    Thanks.
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black
    Tags: None
    #2
    ttt
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

    Comment

      #3
      either you have a short in the wiring harness from alt to cluster or the regulator is bad on the charge lamp circuit. with key on engine off the bulb has power to one side and grounds thru the alt/regulator windings completing the circuit turning the light on (normal) when car is started and reved slightly the wire that provides ground to bulb in cluster now gets power if working properly thus power to both sides of bulb and it turns off *(again normal ) . if that wire stays grounded thru a short the light will stay on ,or the regulator just isnt providing the switchover to power to turn lamp off
      Angus
      88 E30M3 X2
      89 325IX
      92 R100GS/PD
      :)

      Comment

        #4
        That makes sense, thanks. Is the regulator you mentioned something replaceable?

        I know I have a bad solder joint somewhere on the main pcb in the cluster b/c my speedo and econometer die occasionally. Maybe that's related? Then again, that issue has been going on since I've had the car and this is new.
        '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

        Comment

          #5
          yes it is a separate part ,using my 89 IX as an example see this link and item #10

          Just a moment...
          http://realoem.com/bmw/showparts.do?model=1293&mospid=47311&btnr=12_0612&hg=12&fg=22



          enter your vin and search for part # for your model using
          Just a moment...
          http://realoem.com/bmw/select.do


          and search net for best prices,fairly easy to change also
          Angus
          88 E30M3 X2
          89 325IX
          92 R100GS/PD
          :)

          Comment

            #6
            Oh wow, I didn't realize you mean the regulator in the alternator, I was thinking you must be referring to a "regulator" elsewhere... my mistake!

            Thanks for your help! I'm finding them for $45-$50. Heck, maybe I should just pay to have the alternator rebuilt, like I was going to before...
            '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

            Comment

              #7
              I had the same problem. I had the batt light dimming and going away when revs increased. it was the voltage regulator. Got the alt rebuilt. problem solved.
              since it is old -your brushes are probably gone as well. Time for rebuild. they usually last about 80-100k miles.
              sigpic

              Comment

                #8
                ive had this problem twice, both with new altenator and new battery, with new belts, I found that my battery light would come on on start up and go off when i gave it a little bit of gas, like another 200-500 rpm....

                I solved this problem after checking so many things, wiring, voltage reg,..even having new alt checked out,.

                It turned out to be just not enough tension on the alt belt, So i tightened the tensioner a bit, with a new belt , (conti) i found that they stretch just a little bit after a while, anyways, since then it never came back and all my grounds and signals and connections were perfect. voltage is perfect.

                So check your tensioners !!!
                my build here ---> http://www.r3vlimited.com/board/show...ht=lemans+blue

                Comment

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