side view camera

I am installing a 3 camera switcher with rear and side cameras. While I can individually confirm everything is working by applying power to the triggers.. I am having trouble with the side view triggers. (turn signals).   When the vehicle is completely off my turn signals rest at a constant 4V and have a zero volt reading when activated. With the vehicle in the on/acc position my turn signals rest at 13v and have a zero volt reading when activated. I am assuming I need to reverse polarity so that the turn signals will activate the cameras but I need a wiring diagram or help with this. Thank you!

Something is wrong here, they should be zero at rest and 12V+ (nominal) on working. Any way if you're correct you will need this camera.bmp

I'm thinking the trigger for the cameras are being accessed at the turn signal switch wires, not the bulbs or dash indicators. I know Ford has ground inputs to their SJB, the SJB performing the output control. Mark

Thank you for your replies! I have figured this one out for the most part. I installed this on an International truck that's been highly modified. The electronics are all being run off the ISIS Power Multiplexing system. Which I cannot say enough GREAT things about and HIGHLY recommend! I reversed the polarity with one relay from the turn signal output to the camera switch for all cameras.. The only puzzling thing here is when I turn on my turn signals (and the cameras activate perfectly) my rear reverse lights illuminate as well.. :-/

Diode in line with lead to 85, band away from relay? Ween you are so right, I was thinking Ford when I so categorically denied a neg feed then I remembered working on an S Type Jag (A.K.A. town Car) where a bulb in the r/hand rear light cluster wasn't working. I immediately came out with "bad ground". It was of course a bad 12V+ power supply.