i was told to diode isolate the purple wire for the backup camera from the OEM reverse wire --

is that little back cylinder on the purple wire (AVIC purple wire) a diode/fuse inline? Or do I have to add a diode. If so, what direction should the diode go? thanks

There's no diode in the wire, there is a current limit resistor. Why is it that you think you need a diode?

I've read multiple times that it's important to prevent feedback from the AVIC system back to the BCM by using a diode to isolate the circuit from the reverse wire circuit...

any truth to this?

You shouldnt need a diode. But if you insist on installing one, youd want the arrow pointing towards your avic unit.

i have had some cars show that the parking brake was on when it wasnt do to the wire being connected, a diod fixed the problem

and you only want the arrow or line pointing to the AVIC if you have a +pos reverse wire, the arrow or line needs to point towards the wire if you have a -neg reverse wire

Excellent info guys, thank you.

So i installed my F90bt w/ backup camera this weekend --

I ran the purple/white wire straight to the reverse light 12vdc wire and did not use a diode -- all is working fine!

Thanks guys