Speedometer and Trim gauge stopped working

[Covy]

We stored our boat over the winter at a large boat seller / repair shop (indoor). A few things we noticed when we got the boat this summer.

1. Trim stopped working. Button sometimes would put the trim down, but not up. I fixed this yesterday with 2 new solenoids.
2. Some wires were no longer connected. 2 grounds were just not connected anymore, hanging. Fixed that yesterday also.
3. Trim gauge would show trim location, but only partially. Meaning: Trim is all the way down? Gauge might show 1/3 down or 1/2 down. Now it shows nothing (up, which is default)
4. Speedometer worked initially, but as soon as trim gauge started showing nothing - the speedometer stopped as well.

I assume there must be another ground wire not connected properly so that the gauges are not properly referencing ground and, therefore, cannot really read the sensor.

Is there something I can check before I rip the dash apart? I don't want to do that if I don't have to.

 

[Chris1956]

Speedos are usually based upon water pressure. The pickup (pitot tube) often kick up. You might see if you have the speedo on the transom.

As for the trim gauge. They measure variable resistance. Any resistance in the wiring will throw off their accuracy.