wiring lights

[WestTN]

You can do it with two relays, one but one relay and a few diodes are cheaper. Radio shack sells them. Just use one relay and power wire to run the lights and connect a diode from each circuit you mentioned to one side of the relay. run the other relay coil lead to a good ground. Any time you put a relay into a computerized vehicle you should also place a snubber diode across the coil to stop inductive spikes from travelling back through the electrical system. The computers don't like them!