Power trim guage not showing trim level

[bluechevyy]

Ok, I have a 2005 mercury 115hp 4stroke that recently the power trim stopped displaying my trim level on the guage? The guage shows pegged out UP. Does not move when ignition is turned on.

I have recently put a brand new trim sending unit on the outboard which is an exact OEM replacment.

I also have tested both the Trim sending unit and the guage and both appear to be working properly. How I tested...
The trim sending unit I disconnected the brown/wht stripe wire and conected an Ohm meter. Leaving the ground connected to a know good ground. Then I cycled up/down the trim. My Ohms resistance also showed increase/decrease with cycling the trim. So, I believe the sending unit is working.

Then I tested the gauge. Disconnected all wires from the back. There is a purple 12V wire that has power from the ignition, a black wire to ground, and a brown/wht stripe sending wire. Also there is a blue spade connector on back which I believe is power for the illumination of the guage. I connected the power wire to 12V and ground stayed connected. All else removed. Then I crossed the 12V to the sending unit pole and the needle promptly went from pegged full up to down. Think this means the guage is working.

But still the system is not working when I simply use the trim.. How do I move forward to diagnose?? My assumption is the sending unit wiring has a problem?

Thanks in advance for any help..
Curt

 

[Bondo]

Then I crossed the 12V to the sending unit pole and the needle promptly went from pegged full up to down. Think this means the guage is working.

Ayuh,..... It senses resistance to ground, jumpin' power to it is backwards,....