I installed a trim guage on my boat, and I can't get it to work. The motor is a '04 Yamaha 70. I know I have the guage wired correctly, but It still won't work. When I hook up the pink wire to the S terminal on the guage, the needle bottoms out way above the up position. The manual says when this happens there is a bad sending unit, or no continuity. The sending unit has never been hooked up, and I checked it with an ohm meter. I get resistance when I check the pink wire off the sender to my ground on my tester, and black to red on my tester. and nothing when I check pink to red, and black to black. There are no other guages on the boat, and I have found a wiring harness coming out of the control box, so I am assuming that these wires are for the guages? I have my guage hooked to the pink wire coming out of this harness. Any ideas?