Busy Weekend: 911 Targa

Last car of the weekend (I hope) is a 911 Targa that was only 1 headlight working on high beams, no other settings work.  It is all about getting a good case history 🙂  Turns out the owner kept over heating batteries (had gone through about 3 of them), then all of a sudden his headlights started to flicker, then eventually the low beams died, then one high beam gave out.  First thing I did was check the output voltage of the alternator, and just as I suspected, it was putting out almost 15v at idle, which is WAY too high.  The diagnosis, a bad voltage regulator.  When the VR starts to die on the 911’s, symptoms almost always show up in the headlights.  Either it will fry the headlight switch (there is no relay in the headlight system…ouch), or take out the headlights.  Luckily, after testing the voltages on low and high beams at the headlights, it appears our headlight switch is still working find.  The 2 new headlights are a LOT cheaper than the headlight switch.  The alternator needs to be replaced obviously as well.  The VR is internal on this model porsche, so by the time you pay the labor to R&R the alternator, install a VR, you might as well just put in a completely fresh alternator.   Will also knock out an oil change on it, and change the rear deck lid struts.

Testing voltage at the headlights.  Blue/Wh High Beams, Yellow/Green Low Beams

Will tear apart the alternator tomorrow since the new part will not be in until tuesday.


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