mildner

Can anyone help me ?
My 2011 Challenger 210 was under water for a couple of hours and now after cleaning and repairs by the dealership in Cancun Mexico, both engines are running but the starboard engine tachometer has no signal.
I have searched the forums but any mention of the wiring schematics do not match the wire colors in my boat as all references say that the tachometer signal wire is grey, and there are no grey wires coming into my tachometers ??
Can anyone tell me which wire color should be giving the tachometer signal and where I should look for the fault ?
All fuses and breakers have been cleaned and any bad have been replaced, and all connectors have been cleaned.
Thank-you,
Tony