Hi we have a 2000 Cobalt 226 with 7.4 mpi Bravo 3. Today I noticed the trim gauge going crazy - it was bouncing all over the place. Then it would settle down and work fine. Also when we shut the engine instead of the gauge reading down it went to total up. We have Faria gauges -- I checked the outdrive sending units and there were tight - no corrosion at all. While the gauge went nuts the outdrive wasn't bouncing around at all -

Anyone have any ideas to the cause

3pointstar

Bad gauge, loose wire or bad sender.

The wire used to fail where it went thru transom all the time.all my old alpha boats trim gauge never worked.

Thank you so much the input- - It sure would make sense everything else is pretty simple to fail.

3pointstar

Wow , I've got the exact same problem right now too . Except mine coincided with a defective/broken trim motor . (I never did like the way the damn thing sounded , even from new)
I was hoping that when the motor was replaced the gauge would miraculously start acting right again but it didn't so we just disconnected the two wires at the back of the engine that control the gauge and went about our business until the boat comes up at the end of the season .
As I suspected he would the mechanic said it's on the outside of the boat with the sending unit contacts . I guess it's a normal occurrence in my case and has to happen sooner or later (salt water)