The correct functioning of a capacitor can be measured with (for example) a FLUKE multimeter.
The value specified by the manufacturer is 0.22 μF (microfarad). Over time, a capacitor’s performance can be expected to decline.
The left photo shows a broken capacitor: the measured value is 0.131 nF (nanofarad) = 0.000131 μF
The right photo shows a properly functioning capacitor: the measured value is 0.249 μF. This is 13% higher than the specified value, but this does not affect proper operation. The value specified by the manufacturer is a chosen ideal value for the expected average engine rpm. This value is therefore somewhat arbitrary. At a lower value / rpm the contact points will burn in on one side, at a higher value / rpm this will happen on the other side.
Since not everyone has such an expensive multimeter, there is an alternative method to get an impression of the operation of the capacitor. However, this method does not guarantee a correct measurement. See the steps below:
