"John B." wrote:

A great many of those 12 VDC lights are just series circuits made up
of LED's and resisters. Try a resister in series with one side of the
circuit. It may well dim your lights. If that works you can replaced
the resister with a variable resister (potentiometer, rheostat,
whatever) for finer control.


Can and should are two different things. The proper way to dim them
is with a PWM controller which is dirt cheap on Ebay.