Please help with electrical prob on 50 yamaha

[tg9r]

Power trim switch on throttle started blowing main fuse when going up. Have narrowed problem to throttle control. Trim always worked fine using switch on motor, and now it works fine now that I have disconnected a black wire that was connected to the light blue wires that activate the up direction. It now works on the motor and throttle without blowing the main fuse. This black wire goes to both the ignition switch and kill switch. Can I conclude a problem/short in one of these switches because the motor cranks even with this black wire disconnected? Also, any sure way to check these switches before I just start changing? Also, any idea exactly what is this black wire for?
Sorry for the long post but any help would be appreciated.

[CajunChristian]

Black on most motors is a ground. Black is a ground on Tohatsu and Yamaha.
D

[Harley123]

If you can take switch apart and clean it some switches just snap together or screw together some may be glued

[tg9r]

Now knowing that it is a ground wire, I cleaned both grounding connections on motor and battery connections. Still same issue, works fine with ground unplugged but plug ground and up doesn't work then main 20 amp fuse blows.

[Gerald]

Sounds like something is bad with this wire. Maybe you could connect a temporary wire to test if a new wire would correct your problem.

Try connecting a new temprorary ground wire from the battery (-) to the throttle control. Leave the old ground wire disconnected and see if this solves your problem.

If this works.....run a new ground wire to repace the old one.

[LPfishnTIM]

if a ground wire causes a fuse to blow, its because a positive wire is touching something thats grounded, causing a short. I say find which positive wire is shorting out. if you disconnect a ground wire, you run a risk of burning up electrical device if it still works without being grounded. I'm not a mechanic, or an electrician, you can take my advice with a grain of salt, but i've had my share of replacing stuff that I've jacked up, I mostly work on Kohler motors!

[joeymaloz]

unhook everything electrical..... then plug one in at a time when fuse blowes u know whitch circut is giving the trouble...

[Nick1230]

There shouldn't be any black wire connected on ur trim switch, the only black wire used in your whole trim assembly should be a ground from your relay, a trim switch has three wires correct? One is your power supply into the switch, one is you power supply to the up on the trim motor and one is power to the down on the trim motor. Your problem is you are connecting a ground wire to one of the power wires on the trim switch which will cause it to blow a fuse everytime


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[Nick1230]

I'm not by a motor now but I think there's a green, blue and purple wire on ur switch?


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[tg9r]

Nick, I'm pretty sure the ground wire has been connected since the boat was purchased new. You sound pretty sure that it is not necessary for the trim though. The trim motor/relay has a separate ground wire connected directly to the engine block, is this the only necessary ground wire for the T/T system?

[Nick1230]

Is this black wire you are talking about coming out of your control box?


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[budndawn]

Disconnect all wires on both ends and hold one lead of an ohmmeter on the black wire and check for continuity with the rest of the wires. If two wires ohm out then you have a chafe somewhere
... replace both wires

[tg9r]

Nick, this black ground wire in question is coming out of throttle control box. It is also connected to the kill switch and ignition switch then runs to the motor.

[tg9r]

Originally Posted by budndawn

Disconnect all wires on both ends and hold one lead of an ohmmeter on the black wire and check for continuity with the rest of the wires. If two wires ohm out then you have a chafe somewhere
... replace both wires

Good idea, I will do this tonight.
Thanks.

[MossLake]

Originally Posted by Nick1230

There shouldn't be any black wire connected on ur trim switch, the only black wire used in your whole trim assembly should be a ground from your relay, a trim switch has three wires correct? One is your power supply into the switch, one is you power supply to the up on the trim motor and one is power to the down on the trim motor. Your problem is you are connecting a ground wire to one of the power wires on the trim switch which will cause it to blow a fuse everytime

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^^ This makes sense. Switch should only direct power and not be grounded unless it is grounding the case to ground.