Hi all, I hope someone in here can assist me...

APPLICATION: Install interior cold cathode lighting behind the dash on the driver's and passenger sides in a 2006 MINI Cooper S convertable. This lighting would replace my OEM white foot well lighting with brighter, colored light. A second set of cathodes will be placed under the front seats, providing additional foot lighting for the rear passengers.

POWER SOURCE: Due to the MINI's dimming interior lighting, the dealer has recommended tapping into the existing foot well lamps' wiring (the white lights will be disconnected). Due to the cold cathodes' transformer requirements, a RELAY must be installed between the existing wiring and the cathode transformer, otherwise the undervoltage caused by the dimming lights will damage the device. The cathodes only draw minimal power (less than the OEM white lamps) so no additional fuses or other modifications should be required to the fuse block.

QUESTION: How should the relay be wired in this application? I have run across diagrams such as this one:

http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/foglites.htm

...that show how the relay I plan to use should be wired in a traditional, switch-controlled installation, but in my case, how should I connect the positive and negative wires that currently send power to the OEM white lamps, the positive and ground wires leading to the cathode transformer, and the hot wire leading to the battery, so that the existing white lamp current functions, in effect, as the on/off switch? It looks from the diagram linked above that the "30" terminal goes direct to the battery (with a fuse in-line), but what about the other contacts?

Any advice is greatly appreciated!

....Just not sure of the idea of a relay tied into the cars lighting circuit IMO. The driver circuit for the lamps (the ones controlled by the car) may not take well to a relay coil across the output. ( I could be wrong ) I also would think the relay would chatter for a short period when the lamps are dimming out.


Just my 2 cents. Again I could be wrong.

....Just not sure of the idea of a relay tied into the cars lighting circuit IMO. The driver circuit for the lamps (the ones controlled by the car) may not take well to a relay coil across the output. ( I could be wrong ) I also would think the relay would chatter for a short period when the lamps are dimming out.


Just my 2 cents. Again I could be wrong.

Well, the dealer recommended I do it that way, so... Interesting about the relay chatter, though - I hadn't considered that. I guess I could go with LEDs - Oznium sells a bar of LED lamps and they can handle the dimming, but they're not as bright I hear. Cathodes won't deal with the fade - the transformer will be damaged over time.