Volvo Penta SX-M Trim Sender & Gauge Issue

[JLustig]

Last season my trim gauge starting acting up and would show full up or down sporadically while boating and having not adjusted the trim (acting as if an intermittent grounding issue). After inspection a few weeks ago, I found the white wire on the exterior of the sending unit mostly broken. I assumed that was the cause and ordered a replacement sending unit (original part #3855535 removed). I later determined that the white white doesn't actually play any role as the other two wires plug into the connector with the 3rd white wire having no connection. After installing the new after market replacement ordered from Amazon and connecting it up, the trim gauge is only registering about half of the full range on the trim gauge. I've done a little extra testing to ensure the sending unit ohm output is consistent with the old (it is, roughly 1.2-1.4 ohms difference when full up vs full down on the outdrive). Is there a relay in between the sending unit and the trim gauge or a additional transistor or could the gauge itself be the problem? Any suggestions welcomed.

 

[Khris Kraft]

I just did mine. I used one from Volvo Penta and paid lots of dollars for it. After I installed it I stayed in the boat and had my wife hold the sender in her hand and slowly turn the white part. Nothing happened... I then unplugged it and discovered my wires were not pushed into the rubber plug far enough. So I corrected that and had her spin it again and nothing. I asked her if she was turning left and right until it hit the stops. She said yes. Then she announced "it's just spinning now and not stoping" I of course thought she broke it or something... but I looked at the Guage and it was working perfectly. We then turned it left and right a few more times and it's fine. Not sure what how and why it was not working then it was.. but check everything 3 times and maybe you will get what I got. And yea that white wire goes to nothing in my boat also.

 

[JLustig]

I just did mine. I used one from Volvo Penta and paid lots of dollars for it. After I installed it I stayed in the boat and had my wife hold the sender in her hand and slowly turn the white part. Nothing happened... I then unplugged it and discovered my wires were not pushed into the rubber plug far enough. So I corrected that and had her spin it again and nothing. I asked her if she was turning left and right until it hit the stops. She said yes. Then she announced "it's just spinning now and not stoping" I of course thought she broke it or something... but I looked at the Guage and it was working perfectly. We then turned it left and right a few more times and it's fine. Not sure what how and why it was not working then it was.. but check everything 3 times and maybe you will get what I got. And yea that white wire goes to nothing in my boat also.

Thanks for your reply/ post Khris Kraft. To follow-up, hopefully provide some value to others and close out this thread. What I didn't understand at the time, when the key is turned on it powers up one of the two wires to the trim sending unit and the potentiometer inside the sending unit creates resistance (ohms). The ohm values I reported before were recorded without power. When comparing the "new" and old sender ohm reading with power on, it became apparent that the "new" sender was about half the ohms depending on full up vs full down. Bottom line, the "new" trim sending unit is crap! I had purchased this "new" sending unit from Amazon and it was reported as a compatible after market replacement with good ratings. After discovering the ohm difference with the non-OEM sender, I purchased an OEM sending unit from Leaders RPM Shop that I tested and it worked perfectly! Beware of aftermarket cheaper parts is the lesson here.

 

[Khris Kraft]

Thanks for your reply/ post Khris Kraft. To follow-up, hopefully provide some value to others and close out this thread. What I didn't understand at the time, when the key is turned on it powers up one of the two wires to the trim sending unit and the potentiometer inside the sending unit creates resistance (ohms). The ohm values I reported before were recorded without power. When comparing the "new" and old sender ohm reading with power on, it became apparent that the "new" sender was about half the ohms depending on full up vs full down. Bottom line, the "new" trim sending unit is crap! I had purchased this "new" sending unit from Amazon and it was reported as a compatible after market replacement with good ratings. After discovering the ohm difference with the non-OEM sender, I purchased an OEM sending unit from Leaders RPM Shop that I tested and it worked perfectly! Beware of aftermarket cheaper parts is the lesson here.

Yes exactly why I skipped over the $40 ones and paid $205 from volvo. Not very happy at all on the price.. but I can tell you that my last $40 only lasted about a year b4 it started acting screwy at the Guage.