Originally Posted by Ed_r
I need to know how to do this, I think. It makes sense to me but I'm not sure how I'd go about doing it.
Need to wire a relay into the license plate light and the backup camera power wire.
When camera is energized (in reverse) positive power will activate the relay (86 and 85) this causes 30 and 87a to disconnect/open (license light will go out) until camera power is turned off.
86 (coil) = tap camera + wire
85 (coil) = ground - to chassis
30 (common) = cut and run either + or - wire going to license light
87a (normally closed) = run this wire back to opposite side wire coming from the light
87 (normally open) = not used
Single Pole Double Throw (SPDT), Single Pole Single Throw (SPST) Automotive Relays