Trim Gauge Not working

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Trim Gauge Not working

Postby jim_cv23 » Mon May 14, 2012 11:10 am

Mercruiser trim gauge is not working. What is the most likely culprit? Have voltage to one of the two terminals on the gauge. Should I be able to see voltage on both?

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Re: Trim Gauge Not working

Postby Rich_V174SS » Mon May 14, 2012 11:36 am

On the gauge there are 3 wires - power from ignition (usually purple), ground (black), sensor (usually brown). With the ignition on if you touch the sensor wire terminal and the ground terminal together the gauge should peg showing full up trim. If it does the gauge is probably fine. Most of the time the culprit is with the trim sensor on the drive, the internal contacts corrode or the wires fray and break off. Mercury sells a replacement sensor kit that contains both the trim sender and limit pucks for the drive. The hardest part about replacing them is getting to the wire retainer up inside the transom shield above the drive shaft bellows.
Trim Sensors.jpg
1967 V174 Crestflite SuperSport Modified
1986 Mercruiser 190 3.7LX / Alpha One
Rebuild Thread:

1970 V176 Swinger
1983 Mercury 115

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Re: Trim Gauge Not working

Postby Spurlee » Wed May 16, 2012 3:24 pm

Rich is correct. In my case, however, I was able to replace the wires from the gauge sending unit to a point before they entered the transom. The insulation had simply cracked and water had corroded the wires.

Similarly, many years later I was having problems with the trim itself, intermittant action. I examined the throttle switch several times, replaced the pump solinoids and more until I recalled the gauge problem I had earlier.

Sure enough, insulation had cracked and the trim sending unit wires were shorting out against the bell housing. Another external fix and I have been on the water since.

When I eventually replace the bellows and the shift cable I will properly replace the 2 sending unit wires as well.
1990 23CSS - one of the last ones built
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