Trailer Switch Operation

[76SeaRay]

I am switching from OMC to Mercruiser so rebuilding my instrument panel in the process. That means I need to make sure I have all the switches in place correctly. I have the three button Mercruiser Trim/Tilt set of switches and wire harness for the trim pump. It is used, ugly and the switches are in bad shape. I have a binnacle mount shifter with a single momentary switch for up and down power trim built into the handle. I don't want to have two sets of switches for power trim, therefore, I need to wire in a separate Trailer switch on my new instrument panel for use with the binnacle shifter.

A couple of questions:

Does anyone have a schematic that shows the actual wiring of a binnacle with trim only and a separate trailer switch? The only schematic I have been able to find online does not show the wire colors going to which switch so is not clear on what goes to the trim switch in the shift handle and what goes to the trailer switch on the instrument panel.

Additionally, how does the trailer switch operate? Does it bypass the trim limit switch and apply power to tilt up only or does the switch bypass the trim limit switch and apply power up for trailering and power down to trim range after launch? OR, does it simply bypass the trim limit switch and you hold down the trailer switch while pressing the up/down trim switch to power up and down? Definitely could use a schematic of this configuration. I assume the trailer switch is a push and hold momentary switch.

Thanks.

 

[jbcurt00]

Sorry cant help w tilt/trim wiring

I'll leave this here for a couple days, if it doesnt get many (any?) helpful replies, we can move it over to electronics. Then if its still not getting replies, the Mercruiser forum...

 

[alldodge]

Have a diagram but iboats has an issue with IE11 and will not let me upload.

how does the trailer switch operate? Does it bypass the trim limit switch and apply power to tilt up only

Yes, the trailer switch bypasses the trim limit switch on the drive. It connects the Purple/White wire to the Blue/White wire going to the UP relay. The trailer switch has no connection to Down. Use a momentary ON switch for the trailer.

 

[76SeaRay]

So, does the trailer switch apply the power to up as long as you hold it down without holding down the up trim switch at the same time? So, the down trim takes it all the way from trailer position to run position then? Also, forgot to mention, this has dual solenoids on the trim pump. Can you email the wiring diagram?

Thanks.

 

[alldodge]

Your trailer switch should be spring loaded, so the only time it makes connection is when it is being turned ON. When the switch is released the switch returns to the OFF position. It is noted as Momentary, Single Pole, Single Throw Usually a push button type.

In pic below (found on web), note the trailer switch is below the trim up/down

The trailer switch has nothing to do with down, this is fully done by the trim switch by holding it in the down position.

Here is the power trim manual
http://www.boatfix.com/merc/techbk/97/97hs6.pdf​

 

[76SeaRay]

Ok, thanks. The problem with the drawing is that it does not show what wire colors go to which switch and contacts in the shift control handle. Soooo, after studying the drawing, sketching schematics, and studying it -- using the trailer switch to jumper over the limit switch means you must hold the trailer switch down and then press the up trim switch to raise it past the limit level unless I missed something. But since there are no schematics showing exactly how the switch contacts are wired, I think this is correct.

I think I have figured out what I am going to do.......

It appears that one would want the trailer switch to connect to 12v power and to the blu/wht going to the shift control handle instead. This way, it requires just the trailer switch to move it all the way up. A relay could have the power only available to the trailer switch when the ignition.

Up trim switch position on shifter -- Red/Purple is connected to Purple/White through the trim switch (Up solenoid on)
Dn trim switch position on shifter -- Red/Purple is connected to Green/White through the trim switch (Dn solenoid on)
Neutral trim switch position on shifter -- Open connections to Purple/White and Green/White (Both solenoids off)

Trailer switch on instrument panel -- Red/Purple is connected to Blue/White (Up solenoid on independent of trim limit)

I may make mine use the trailer switch to both lift and lower, make the trailer switch SPDT On-Off-On momentary.

Trailer switch on instrument panel -- Red/Purple is connected to Blue/White through the trailer switch (Up solenoid on independent of trim limit)
Trailer switch on instrument panel -- Red/Purple is connected to Green/White through the trailer switch (Dn solenoid on independent of trim limit)

This then operates like the Trim switch except it by passes the limit switch. I plan to use a relay in serial with the trailer switch, a SPDT 2 Position NC NO relay, to enable the trailer switch only with the ignition off. Wire the relay common tab to Red/Purple, normally closed tab to one contact of the trailer switch and the Blue/White to the other contact on the trailer switch (relay normally open tab has no connection). Wire the relay coil to the ignition. With ignition on the relay opens and no power is available to the trailer switch, with ignition off relay closes and provides power to operate the trailer switch. I haven't figured out the fuses yet in the circuit.

This is for info only as what I plan to do... It has not been tested... Not responsible for its use on any boat other than my own.

 

[alldodge]

Sure wish I could upload, my head hurts
This is correct

Up trim switch position on shifter -- Red/Purple is connected to Purple/White through the trim switch (Up solenoid on)
Dn trim switch position on shifter -- Red/Purple is connected to Green/White through the trim switch (Dn solenoid on)
Neutral trim switch position on shifter -- Open connections to Purple/White and Green/White (Both solenoids off)

Trailer switch on instrument panel -- Red/Purple is connected to Blue/White (Up solenoid on independent of trim limit)

You can do this, but your making it more complex. You could just bypass (don't use) the trim limit switch on drive, and then the trim switch can bring the drive full up or full down with just the trim button.

I may make mine use the trailer switch to both lift and lower, make the trailer switch SPDT On-Off-On momentary

You only need a limit switch for folks that would not pay attention and over trim while running