I have a 2005 Vanden Plas XJ8 that I recently put in a NavTool NavRGB device to switch the navigation screen to the backup camera image. Everything works great, but my battery gets drained down to 9 volts overnight. I suspect it is that the backup light wire for the ground trigger to the relay is where my problem is. I know this wire provides 12V all the time except switches to ground when the car is put in reverse. Is there a way I can keep the 12V positive from going to the relay, but allow the ground to pass to the relay? Below is how I have the relay wired.


Wire used from left tail light to relay.

Is this normal for the relay to drain the battery when car is turned off? How can I work around this problem?
Thanks,
Kevin

 

Well, I think I found my answer to keep the battery from draining when using the backup light wire to trigger the relay. I found an article that explains diodes and think if I put one between the reverse light wire and the relay pin 85 it will keep the constant power from the light from getting to the relay and draining my battery. From the below diagram you will see that the diode blocks voltage, but allows the ground connection through. At least on the bench test it work as described. I will try it in the car tomorrow once the rain stops.