Drive Trim Sensor repalcement?


vmaxhp

vmaxhp

New member
Good evening,
I have an 07 34PC. The port stern drive trim sensor isn't working properly. The drive does go up and down with the switch. Just not being displayed correctly. Typically, that's the trim sensor. Has anyone replaced the trim sender themselves? How does the wire get routed in from the transom, and where does it terminate? I believe there's two sensor per drive, correct? I believe this is the part:
https://www.wholesalemarine.com/mercruiser-trim-limit-and-sender-kit.html
Thanks!
Rick
 
There is a trim 'sender' on the starboard side of the drive and a trim 'limit' switch on the port side of the drive. They are sold as sets, so eventhough only one of the 2 are bad, you typically have to buy both. Might as well replace both while you are at it.

I have replaced the senders a few times, it is wicked fun.

The wiring routes through the transom assembly at the upper portion. The wires have a section on them that form a grommet and there is a retaining plate that holds them tightly to the transom opening, creating a water tight seal.

The wires connect to the mating wires at the rear of the engine.

The service manual says to take the outdrive off and remove the bell housing in order to gain access to the retaining plate to remove the old wiring and install the new. However, I have done the replacement without taking things apart, using a 1/4" drive socket.

I'd say the job is a 6 on a 10 scale.
 
I might be doing this to my port this winter. Should have just done it when the drive and bell housing were off... but It appeared they worked at that point.
 
Do you have a pdf of the Service Manual by chance? :)
The limit is working, the position sensor is not, or working erratically. Per a couple of videos, the position sensor is based on a wrapped resistor wire. It seems the seal can fail on the sensor housing, allowing water and debris to enter the sensor, and potentially changing the resistance of the pickup across the wire. If the wire through the transom is ok, looks like it might be possible to refurb the position sensor with new parts, without having to change the wire.
Thoughts?
tpenfield said:
There is a trim 'sender' on the starboard side of the drive and a trim 'limit' switch on the port side of the drive. They are sold as sets, so eventhough only one of the 2 are bad, you typically have to buy both. Might as well replace both while you are at it.

I have replaced the senders a few times, it is wicked fun.

The wiring routes through the transom assembly at the upper portion. The wires have a section on them that form a grommet and there is a retaining plate that holds them tightly to the transom opening, creating a water tight seal.

The wires connect to the mating wires at the rear of the engine.

The service manual says to take the outdrive off and remove the bell housing in order to gain access to the retaining plate to remove the old wiring and install the new. However, I have done the replacement without taking things apart, using a 1/4" drive socket.

I'd say the job is a 6 on a 10 scale.
Click to expand...
 
You *could* open the trim sender and see if you can clean things out. I think the newer versions are a carbon film deposited resistor type of potentiometer. Odds are the internals are trashed from the water exposure.

Some folks have tried splicing the new sender into the old wiring to avoid the thru-transom work. . . . that probably works for a while . . .
 
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