Help troubleshooting back-up camera

[Karter]

My camera has worked on and off for the last few months, now it is definitely off! The cable wire goes under the headliner and out the back of the unit so no access point I can see. What steps would you take in trouble shooting this please? I feel like I have a bad connection because it has worked intermittently. It simply won't come on now. Thanks for any and all help!

[Joshua Cavitt]

You could start by following the wires to the multiplexing system down below the dash.