On Jun 23, 10:14 pm, "hr(bob) "
wrote:
The much lower voltage measured across the switch
shows that something is partially shorting out inside the switch, and
the other readings are normal.

Except he took that reading with the switch open, which means he's
reading from hot, through the light to ground, and the switch is not
in his circuit.

If this is a fluorescent light and especially if he's using a digital
meter also, the reading is suspect at best.

John, the best way to test the circuit and the possible failure modes
will depend on the type of light you have (incandescent, compact
fluorescent, fluorescent tube). If it's a compact fluorescent,
temporarily replacing the bulb with an incandescent bulb will make it
easier to debug.