Reversing camera no signal 2004 Toyota RAV4

[Tom4292]

Hi there, I just bought a 2004 Toyota RAV4 top of the range model with a built-in sat nav which I have managed to get working by changing the fuse. However when I put it into reverse it comes up with no signal for the reversing light which is still intact as far as I can see below the reg plate at the back. If anyone happens to know any suggestions on how to get it working that would be much appreciated I'm thinking it's the fuse but I don't know where it's located and I've tried looking it up online on the website which I found for fixing the sat nav but it does not specify which one is for the reversing light many thanks.