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Old 01-08-2020, 02:02 PM   #567
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Join Date: Sep 2013
Location: Montreal, QC. (currently expat to Shanghai)
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Originally Posted by geraintthomas View Post
Interesting! I'll check with another. You set it to 20v right?
DMM set of 20V(dc) is correct.

The +2V difference from car OFF to ON is sufficient to confirm your alternator is still in good shape and charging.

I'm guessing your DMM just needs to be re-calibrated. If you pop open the enclosure you should find 1 (or more) resistor/potentiometer. One of those should be for voltage offsetting (you'll need a known voltage source to calibrate it). Plenty of tut online/YT.
'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
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