Reverse camera problem

I have connected into the red green wire on the ecu to the reverse camera wire on the head unit.
When I put car into reverse, camera appears on the screen for a few seconds then goes back to main screen then back to cam view the. Back to main screen occasionally flashing no signal when camera view comes on!.
It's like the red green wire is pulsing .
camera is powered from reverse light feed at rear of car so camera only activates when in reverse, and red green link to head unit only activated when car goes into reverse.
Anyone else had issues ( before I blame head unit!
Ta :)

Did you fix this issue? I'm looking for a place to send the reverse signal to my headunit

When I installed my camera last year, I found a feed in the stereo loom. I just had the voltmeter on wire after wire until I found one that came on in reverse only. This is on an auto though.

For me it was a bad connection, ( or a not good connection that became a bad connection toon when the interior panels were put back in!.
Passenger side kick panel remove and you find Autobox Ecu, it is the green and red wire :)