OX66 won't trim up, chasing down Sb

[mesias_yam]

Hey guys,

Long story short, I reinstall this motor (2001 SX225TXRZ) after almost two years repairing the boat. Some issues appeared of course... this post is related to the motor not tilting/trimming up from the remote control. Tilt down works just fine and I can tilt it up from the trailer tilt switch.

I ruled out all remote control switches, remote control harness and main harness. I currently jumped 12v directly in the Sb wire going back to the motor. I read 12v at the motor side of the main harness but no voltage at the relay connector. When I activate the trailer tilt switch I get voltage at the relay connector.

I noticed a small black cube where all three trim/tilt wires are going but I'm not sure what it is... is it a fuse? The wiring diagram doesn't show anything else on the way... any ideas?

[rodbolt17]

the helm switch uses a different power supply than the pan switch.
is this a twin engine setup?

[mesias_yam]

Yes, LX225TXRZ and SX225TXRZ.

I'm feeding the SX 12v into the Sb wire from the LX remote control harness red wire. I could make a jumper cable but this was easier.

[boscoe99]

I am guessing that it is a diode assembly. If there are three wires. One sky blue, one grass green and one black.

[mesias_yam]

I'm using as reference the page 8-43 from the service manual...

If I'm reading it correctly the same Red wire from a 30A fuse is feeding the Trailer switch and it's also going thru the main harness to the remote control which I assume feed back the switches.

I see no diode in the diagram... Here is a picture of the part:

[boscoe99]

I'm using as reference the page 8-43 from the service manual...

If I'm reading it correctly the same Red wire from a 30A fuse is feeding the Trailer switch and it's also going thru the main harness to the remote control which I assume feed back the switches.

I see no diode in the diagram... Here is a picture of the part:

That is the diode assembly. Three wires. Blue, black and green. It is not always shown in the Yamaha diagrams. Same thing with wires, connectors, components and such. The documentation is the tail end of the dog and much gets overlooked. Notice how the wire color don't stay the same some times when they cross a connector? WTF!

I see the same thing that you do. Same power supply used for both trim and tilt switches.

[mesias_yam]

Nice! The colors help a lot... What's the role of the diode in this circuit? I checked and it's not getting voltage in any wire.

[boscoe99]

Nice! The colors help a lot... What's the role of the diode in this circuit? I checked and it's not getting voltage in any wire.

When the trim/tilt relays are unpowered (when the switch is released) high voltage is induced into the coil wires. The diodes block that voltage from going somewhere and doing damage.

[ausnoelm]

What induces this high voltage?

[99yam40]

breaking of the current flow is the best way to describe it I guess.
collapsing of the magnetic field causes the spike

[mesias_yam]

I checked continuity between the Sb socket at the motor harness and the double white wires and there is not. There is tho for the Lg socket and the light green wire at the diode. I guess I have to pull the harness to see the actual wires.

I also checked additional wiring schematics from the manual. The diode only blocks the voltage from the cowling switch to go back into the remote control. Sb and Lg from the cowling switch is tied together at the diode with the Sb and Lg coming from the remote control.

[boscoe99]

What induces this high voltage?

https://www.allaboutcircuits.com/tex...ting-circuits/

[boscoe99]

I checked continuity between the Sb socket at the motor harness and the double white wires and there is not. [/IMG]

What is this all about? The white wires part that is.

All of the Sb wires are common. From either switch to the relay.

All of the Lg wires are common. From either switch to the relay.

Thanks for finding the diode assembly.

[mesias_yam]

The wires coming out of the harness to the diode assembly are white or the sky blue faded tremendously. LOL... Take another look at the picture. Outside those, all other trim/tilt wires look as expected (Sb or Lg).

I pulled the harness out... but started raining of course. I hope I'll remember all connections later.

[boscoe99]

The wires coming out of the harness to the diode assembly are white or the sky blue faded tremendously. LOL... Take another look at the picture. Outside those, all other trim/tilt wires look as expected (Sb or Lg).

I pulled the harness out... but started raining of course. I hope I'll remember all connections later.

That would be my guess.