Porsche Enthusiasts Club Forum

An update, and to close this one off.

Before I stripped down the instrument cluster I thought I would take a few more last checks.

Checked voltage at the exciter wire - 12 volts when ignition switched on. But still no light on the gauge.

Larger wire - permanently 12 volts.

And then I recalled I had recently picked up a spare alternator as part of a members garage clear out. This one needed a new fan, but was otherwise working.

So I rested this one on the strut top and connected the wires from the one in the car onto this spare, and then earthed the casing onto the block via a jump lead.

Turned the key, and hey presto, light on at the gauge! This means that despite a new voltage regulator the existing alternator was duff.

Swapped the fans over and spare alternator installed - started car, now showing warning light on key position 2, and healthy voltage when running and no light.

looks like the problem is solved, and the lesson is, think very carefully about trying to do a DIY repair to a duff alternator with a new voltage regulator. For me, in future when they're gone, a new one, or a professionally rebuilt one will be the only route.

Thanks again to everyone for the help, ideas, advice. Really appreciate it.

Correct charge light and its association is basic. Worth fitting new globule and checking the associations with it. Or on the other hand it could be an awful controller. With the motor running and a multimeter over the yield of the alternator then you ought to draw near to 14V with a touch of throttle. The equivalent over the battery. Likewise check the battery associations are tight with no volt drop to earth which isn't obscure on these.