87 Merc 115 trim sender issue

[archbuilder]

Any one know how to test a mercury trim sender? I have a new gauge (Faria) and a new Mercury trim sender. When the motor goes up, the gauge goes down. I thought I had the wrong gauge, but I check the part number and it should be the right gauge. The sending unit looked just like the old one. I also tried mounting the sending unit 180 degrees from where I had it originally. Same results. I was hoping to test the sending unit so I can rule it out as the problem. Is it a resistance measurement? If so any idea what the output should be? Thanks

 

[Barnacle_Bill]

Re: 87 Merc 115 trim sender issue

Reverse the wires going to the sender.

 

[Faztbullet]

Re: 87 Merc 115 trim sender issue

Here is ohms value for senders...
http://faria-instruments.com/site_manuals/IS0085E.pdf

 

[archbuilder]

Re: 87 Merc 115 trim sender issue

If I recall correctly there is only a ground that hooks up the mounting screw and the "sender" wire. I'll check the output tonight. Thanks for the help.