Logo
FULL SITE MENU

Checking trim wiring

R

Ricksrinker

New member
I have an o7 350 mpi with a bravo three and a trim issue. The trailer up and trim down work but trim up does not...and never has.
First check was to jump the trim limiter to rule that out. I also had already tested the selonoids jumping those. I pulled the plug at the pump and tested the harness side continuity foe the trim switch at the handle and trim up failed. I could not locate on this site trim components and was looking if the handle it self is serviceable?
 
Follow the twp pairs of black wires from trim sender and trim limit on drive to Pump.

There should be a small plastic wire holder which will have the trim limit wiring, There may be a jumper installed (two male bullet pin jumper)

what may have happened is, the limit switch may have stopped working and they Jumped out the limit switch at where I described.
When this is done it allows trim up all the way from the full down position to the full up position with only the rocker switch negating the trailer button.


I have done this many times to allow boat to be used and replace limit switch when boat is out of the water and can be serviced

Limit switch wiring.jpg
 
Disregard prior post, Miss read your post.

Looks like you either have a bad trim rocker switch or a bad connection at handle or from handle into wire harness

WHat shift control do you have and is the trailer button separate from the trim up/down button
 
Jack - Same generation of boat. I've replaced both solenoids due to failure (C and D). You state: "I have done this many time..." Do you have a limit switch P/N? Difficult to do? Where is this limit switch? Special instructions? Thanks
 
Hi Jack, thanks for the reply. My control has a 3 position control for the trim..down, up and trailer. I THINK with my limited knowlege it is in that switch as I can get continuity through the blue wire at the plug at the pump in the trailer up, down but not trim up....and both the trim up and trailer go through that same wire so I have to assume, I THINK that the circuit in the harness is ok and that 3 position rocker switch is bad....I don't see a plug near the control unit to unplug it unless it is a very long pigtail buried in the bundle of harness it goes into....
 
Have you checked the limit switch? You did not describe your trim issue but if it won't go up it may be that limit switch- it plugs into the harness at the plug at the trim...pull that loom apart and you should have two black heavy wires that are butt plug ins...pull that apart and jump it on the harness side which bypasses it. If it then works then that is the issue- but, your looking at pulling the outdrive to install a new one as the wires route throught the transom......good luck!
 
The trim Limit switch is on the outdrive at the pivot point. A black plastic puck, one on both sides. The drivers side is trim position and the passenger side is the trim limit.

The trim limit is a ON/OFF switch. 12 volts passes thru this switch to the up solenoid.

There are two Phillips head screws to loosen that adjust the UP limit when using the TRIM switch. (Up limit is the usable limit before cavitation occurs).

The reason for TWO wires on one side shown in the image for the up Circuit is, When the trailer button is pressed it Bypasses the trim up circuit and applies 12 directly to the up solenoid by way of one of the blue/white wires. Note: Both wires joined together at one side (female bullet connector).

(Note: the wire connection with two wires on same bullet connector (trailer mode), One is from control handle switch (trailer) and the other goes to the trim up solenoid on pump) (the single wire is from the trim up switch and goes thru the limit switch back on outdrive and back to the two wire connector as one of the wires of the two goes directly to the up solenoid)

The images shows this i attached in my first reply. You need to find that connection in the harness.

You can then, using a test light or volt meter (test light preferred), disconnect the two bullet connectors.
The single wire is the trim switch wire from control handle. The two wire is the Trailer switch wire from control handle.


You can then push trim switch at control handle and if you have light/voltage then the trim switch is working.

You already know the trailer is working.

When you say 3 position control, you mean that you have,
1. One rocker switch, it has three functions? Trim up/down and an over push activates trailer up?

or

2. Two switches and one is Trim up/down and the second switch is Trailer?

I am still not clear....
 
Last edited:
wow , thanks for the breakdown....I'm not an electrical person...but really trying to learn more...i can deal with most mechanical stuff but this...devils magic in them wires! So, my handle has a single rocker switch that has the three positions. I believe I mentioned when I purchased, this is the way it worked. I like to keep the boat "sellable condition" and to me that means everything needs to work. Also, during ownership, the transom was leaking at the merc seal so I divised a way to pull the motor, disasemble and repair and put it back together and during that time, I did replace the limit and positon senders but could never get the limit to work....I assume it all ties in together.
I opened the access right beside it and I can feel about a foot of the wiring before it buries into a large bundle of wires. I can get into the area via another access point and cut the wire ties to expose more of the harness...
As far as additional testing for the up you descibe above...I'm I learning anything new? Selonids are working, I have the limit switch jumped and have confirmed there is no continunity through the harness from from the switch to the plug....
 
Continuity is not the right term here.

You are checking for signals (voltage).

Continuity is a resistance measurement such as using an ohm meter to test a fuse. If fuse is good it reads it has continuity if fuse is blown then it is open - no continuity.

Anyway,

Two things come to mind,

1. is there an issue with the switch? You would need to disassemble the hand control to test switch. Switch will have power to switch which is then sent to (trim up, trailer and trim down) most likely internal of switch. (with battery power disconnected!!) you can use ohm (continuity check) on switch. Fond power in and connect one lead, then use other lead to check if each makes or not

2. If not switch and it works in all three positions then you need to see if the wire from trim position on switch is intact and this would be where you would check continuity to the one wire connection described before that you may need to look for.
 
So, I was able to test the switch and up did not work so I did get a new one...and that seems to be now hood. As I was reassembling and fill the reservoir the remaing fluid was pinkish so assume I have water in the system. I pulled the reservoir and seevwhere the screws hold it on there is a crack. I have ordered a new one...what about what is in the system...is there a way to flush out the trim cylinders? Can't imagine it would be good for them....hard to tell how long it's been that way. I can pull the lines off, can I blow them out with air?
 
The reason its pink is someone used GM transmission fluid. Go buy two quarts of power steering fluid at any auto parts store.
Trim drive all the way down ro collasp trim rams. You are installing new resevoir so fill with power steering fluid. rund drive all the way up and down several times. Return to full down position. check fluid level. if still milky you need to suck it out. you can use a turkey baster if thats all you have. Repeat this several times until fluid stays clean. Note; If fluid is airated that is normal and the air bubbles will dissapate. Also the red cap has a pin hole in it. thats the vent!!!!
 
Ricksrinker said:
So, I was able to test the switch and up did not work so I did get a new one...and that seems to be now hood. As I was reassembling and fill the reservoir the remaing fluid was pinkish so assume I have water in the system. I pulled the reservoir and seevwhere the screws hold it on there is a crack. I have ordered a new one...what about what is in the system...is there a way to flush out the trim cylinders? Can't imagine it would be good for them....hard to tell how long it's been that way. I can pull the lines off, can I blow them out with air?
Click to expand...

Ayuh,..... Before you hook it all back up, put the ends of the lines in a catch can, 'n lift/ lower the drive manually, to clear out as much oil as possible,......
Then proceed as Jack describes, to clear any remainin' contaminants,.....
Cycling the drive on the pump a few times will also bleed any air outa the system,....
 
Back
Top