Trim gauge reading backwards

[mrandmrsalf]

I have a 1977 Johnson 85HP model number 85ETLR77S. My trim gauge is reading backwards for some reason. When I trim down, the gauge goes to the up position instead of down and vice versa. Also, the gauge is only reading 3/4 when trimming up and the tilt kicks in so basically the gauge is only moving about 1/4 of its travel. I have read other threads that mention something about a sending unit tab of some sort that frequently breaks but apparently this motor does not have one of those. At least if it does, I cant find it anywhere.

When I bought the boat last summer, the gauge didnt work at all. I just got the gauge working recently. I took it out and cleaned up the connections. There is some sort of diode or resister on the back of it...could installing this backwards cause this problem? I have also been told that if a Mercury style gauge is installed, it will read backwards. I dont know if its a Merc gauge but I do know that all the gauges installed are the same style and appear to be about the same age...very old (wouldnt be surprised if they were original)

Its really not that big of a deal as I have gotten use to how it works but Im just kind of curious why this is doing it or how I could fix it.

Any ideas?

 

[ezeke]

Re: Trim gauge reading backwards

The trim gauge is for the range of the trim or 15 degrees +/-.

The trim gauge sender is a variable resistor on the transom bracket; if the gauge reads backwards, the wiring is reversed.

The wiring on the gauge should be Brown with Black to G. Brown with White to S, and Purple (positive voltage from the control) to I.