Mercruiser Trim Sender Problem

[jmadisonbiii]

My trim gauge sender broke, so I replaced it today with a new sender by cutting the wires and splicing to the old ones, which were in fine shape. When I wired up the new sender, it would only jump from full down to full up, with no sweep. Everything worked great before I physically damaged the old sender. I did install the starboard sender, not port, although it’s behaving like the on/off port sender. Any ideas?

 

[Bt Doctur]

What letters are embossed on the side of the sender

 

[Maclin]

What @Bt Doctur doctor said....the new one acts more like a trim limit switch, but I do not know myself if it would install on the gauge sender side.

 

[jmadisonbiii]

I can’t check the new sender installed till in the morning but the other sender in the pair (not installed) is marked PORT TRIM LIMIT. I believe the new unit on the boat, just like the old one says STARBOARD TRIM SENDER

 

[Maclin]

I apologize, I reread the end of your post and it sounds like correct one.

 

[Bt Doctur]

did you check the index mark?

 

[wellcraft-classic210]

If your not have any luck with adjustments :


The sender is a variable resistor that can be easily checked with a multi meter // The gauge must be designed to work with that sender // You also need a good 12 volt signal to the gauge and ground for the circuit.

Their should be some resistance charts with expected values that you can use the verify the sender and wiring with a multi meter.

 

[jmadisonbiii]

Update: I aligned the index markers, turned the key on, slowly turned the rotor by hand and after about 50 or 60 degrees it jumped to full up. Same thing going the other way. Could I have damaged the gauge by grounding the hot wire while installing? The new sender IS marked STARBOARD TRIM SENDER and is OEM

 

[wellcraft-classic210]

Hard to say -- without doing some meter checks // Do you have access to one // Know how to use one ?


-- Are you sure that gauge is compatible with Mercruiser ?

 

[alldodge]

Update: I aligned the index markers, turned the key on, slowly turned the rotor by hand and after about 50 or 60 degrees it jumped to full up. Same thing going the other way. Could I have damaged the gauge by grounding the hot wire while installing? The new sender IS marked STARBOARD TRIM SENDER and is OEM

What about turning the other direction?

You wouldn't damage the gauge by grounding the sender lead

 

[rickasbury]

I'm watching this as I had a similar issue- I did a bellows repair- everything was working fine before I tore it down...put it back together, trim went up and down but nothing on the gauge and no "limit" control either. was convinced that the senders were bad, bench tested out of the boat and could get no readings- which made no sense to me that you could test without them hooked up to something- ordered new ones as I had another issue and have removed the transom assembly....

 

[wellcraft-classic210]

You should be able to some tests either way --

The meter MUST be setup correctly & each test type will have its own merits & detractors. If you sensor was OPEN and faulty then you would not get a variable reading for the resistances.


On the boat with power on -- Current & Voltage tests

On or off the boat with power off -- Resistance checks ( I would probably start here )


I can help with the steps to do this if needed as this can be tricky if you have not done it before -- But its not that hard..

 

[wellcraft-classic210]

Mercruiser's trim-sender is a potentiometric one with a down-resistance of 10 Ohms and an up-resistance of 167 Ohms.


(Values for ohm meter testing -- 10-167 ohms across the 2 wires. )

With a Multi meter on ohm setting with leads in plugged into correct positions ( verify meter work by touching leads together and getting something close to 0 ohms on meter indicator )

Connect the meter leads to the 2 trim sensor wires ( These should be disconnected from boat )

Spin the sensor housing to center section & look for readings that are variable as it turns and in this range.

If that checks out its something besides the sensor

 

[jmadisonbiii]

I will test with a meter both with and without power, both voltage and resistance and post. Thanks.

 

[rickasbury]

huh, then what I was told was correct, just a mystery as to what happened....both sensors were bad then, I even bought a new meter as the one I had I was not confident in- not that I know much about operating one! but, I did my test off the boat, set the ohm meter on a setting (tried them all) and spun the dial and got zip. Just a mystery however that both worked and then they didn't.....new ones from China 55 bucks, we will see...at least I know I can test them before I install them!

 

[rickasbury]

Thanks for the simply testing instructions!

 

[jmadisonbiii]

OK so I tested the questionable sender with a multimeter: 0 ohms when indexed, rotated a little and it jumped to 225. Over and over , same spot. So I decided to check the other new sender marked “PORT TRIM LIMIT”. The meter slowly went from 0 to about 175. The covers were mismatched. I swapped covers, wired up the proper trim gauge sender, perfect sweep on the gauge. Thanks for all the help.

 

[Maclin]

Glad you found it, that is what it acted like for sure. Someone had swapped covers, sheesh.

 

[alldodge]

Swapped covers that's a new one, good to know thanks.
Wonder if that is another quality control issue with Sierra

 

[jmadisonbiii]

These are actually Quicksilver OEM. Kinda makes you wonder