2013 Yamaha F25 trim relay assembly ground point not grounding

[dgarrison]

Troubleshooting a trim system that stopped working. Discovered that the ground point on the engine block is not grounding (point on block where black wire from trim relay assembly attaches). I can disconnect the black wire (originating from trim relay assembly) from the factory ground point and ground it just about anywhere else on the motor and everything works fine. The voltage meter does not compete a circuit when I check the factory ground point. How is this possible?

 

[boscoe99]

Any point on the block is going to be grounded to any other point on the block. Put your multi-meter on the ohms or continuity setting and see for yourself.

I can see an internal wire failure such that when the wire is placed in one position it works and when placed in another position it does not work.

 

[99yam40]

my guess would be corrosion or oxidation where that wire was bolted on

 

[GA_Boater]

my guess would be corrosion or oxidation where that wire was bolted on

This my first guess. Or a bad crimp on the ring lug that happened to work better after the move to another point.

Don't quite understand this "The voltage meter does not compete a circuit when I check the factory ground point." Ground checks are done by checking continuity on the Ohms scale.

 

[dgarrison]

Hard to believe, but just checking for continuity with ohm meter, the factory ground point will no longer complete a circuit, but the bolt just next to it will complete the circuit. I have the wire disconnected in this image. Totally corrosion free. WTF??? I am afraid to change the factory ground point for fear of pushing 30 amps through a different part of the motor. I can add an extension wire to the black lead from the relay assembly and make the tilt/trim work by grounding it just about anywhere on the motor - except where it is supposed to go.

 

[GA_Boater]

Use the other bolt. It looks like both bolts are into the same part of the motor - The block.

 

[dgarrison]

Using a different ground is plan B. But there has to be some reason for the existing ground point to suddenly not complete the circuit. Perhaps some other wire or jumper that grounds that part of the block has failed. Hoping someone has seen this before

 

[GA_Boater]

Has any recent work been done on the motor before it quit working?

Forgive our manners. :welcome: aboard.

 

[99yam40]

pull the bolt back out and clean the threads of the bolt and hole along with the contact surfaces of bolt and block

 

[dgarrison]

Thanks everyone for your input. This is a real head-scratcher. No major service other than fluid change and new impeller. Was working fine. Raised it to top position and then when trying to lower it stopped. I replaced the relay assembly, but when that did not work I began testing all of the connections and isolated the problem to this ground point. The motor has less than 50 hours on it and everything look brand new. I will try scrubbing the contact surfaces, but even with the bolt out of the block the contact surface on the block will not complete the circuit.

 

[boscoe99]

I am afraid to change the factory ground point for fear of pushing 30 amps through a different part of the motor.

The ground wire from the relay sees minimal current. Probably less than an ampere.