Trim Gauge Signal Range

[Ralop]

I'm trying to find out why my trim gauge is not working properly. I have a 1994 Bayliner Capri 2050, Mercruizer Alpha One Gen II. I bought the boat late last year and the trim gauge appeared to be working at first but at the second time on the lake the gauge went in to the red zone (up position) and staid there.
I just took out the gauge to check the voltage and here is what I found.
In up position I measured 5.8V and in complete down position I measured 5.0V on the signal terminal. That does not look like the range I would have expected, but it does eliminate a broken wire.
Does any one know the voltage range for the signal going to the trim gauge?
The gauge seams to work fine. I jumpered ground to the signal terminal and it went to complete down position. It is a Quicksilver gauge.

Thanks in advance for your help. I'm a new boat owner and new to the forum and certainly could use some help.

 

[jhebert]

Re: Trim Gauge Signal Range

Disconnect any wires to the trim position sensor. Measure its resistance at the maximum up and maximum down positions. Usually the resistance range falls into a particular range, but I am not familiar with the resistance range for particular engine. The current to the trim sensor is usually supplied from the battery positive (+12-Volts) with a fixed resistance in series, sometimes around 47-ohms.

Sometimes an isolated ground return is used to return the trim sensor low-side back to the gauge, but other times the ground is picked up locally near the sensor. The sensor ground and the trim indicator ground must be at the same potential. If either device has a poor ground you will get unusual readings. Check the ground path at both the trim sensor and the trim indicator.

 

[Ralop]

Re: Trim Gauge Signal Range

Thanks for the info. I have not had a chance to look at the grounding yet. But that seams like a reasonable cause. I'm rebuilding the trim cylinders right now. Once I have them back on I will get back to the trim limit and position sensor.