if i may resurrect this thread, i have the same problem (although the symptom is different). i think the noise on the signal light is caused by the 'hot check' of the light.

i have done the below tests:
Scenario 1. engine not running, key in position 2, put gear gear into reverse-> relay engages, camera works perfectly.

Scenario 2. engine running (key in position 2), put gear into reverse-> relay starts making a continuous pulsating 'TRRRRRR' noise! audibly it must be like 10htz or so.. the camera still works because the frequency is enough to flip the video module to show the camera feed. but occasionally the screen flickers (so i don't have lines going across the display etc).

the bulbs have a hot check and a cold check. so i assumed this to be the hot check that is coming out as noise.

in fact i did a further test: while in Scenario 2 above, i touched a direct +12v onto the reverse light pin (87) on the relay (through a 5A fuse just in case). and sure enough the relay stops pulsating and sure enough, a 'Check Reverse Lights' comes up when the key is later turned off. this is why i assumed it must be the hot check causing the noise.


in any case adding the second relay wouldn't stop the relay pulsating at the frequency of the light check. it possibly fixes the problem by synchronizing the NTSC timing of the camera by giving the same pulse onto the other wire of the camera?

what i'd like to do is to create scenario 1 ie hold the relay down without making it go TRRRRR.. isn't there a way to do this, options in my mind:

1. switch off the hot check of reverse lights (but how?)
2. a 2000uf (too high?) or so capacitor across pins 85 and 87 (relay would stop pulsating but that might impact the light check).
3. a 2000uf or so capacitor across pins 30 and 87? (relay would still pulsate but the video module would get a constant feed.. hopefully).