I just installed gauges in my car and wanted them to dim also. I decided to splice into the heating controls lighting since it's a lot easier to get to than removing the gauge cluster. I first tried it by splicing into just the power wire and grounding it somewhere else, but they wouldn't dim. Then I moved my ground wires and spliced them into the ground wire for the heater control lighting and they dim with the instrument panel now! Just so you know, I have two A-pillar gauges and two mounted on the steering column, and it really wasn't hard to run the wires! Good luck!