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1990 Yamaha 115 ignition switch issues?

Pianotunernj

New member
Ok, so I’ve had this boat/motor for 20 years, never a problem in all that time, freshwater and salt. Last trip out in November, I attempted to start the boat at the ramp and first attempt the engine cranked, it usually takes a few attempts. Second try, nothing. After messing with key I heard a pop from the ignition area (my buddy heard it too) so now I’m assuming the ignition switch (side mounted controls) has finally given up.

Over the winter I ordered a new switch. Slightly different, now the choke is built into key switch, replacing the toggle choke, no biggie. Otherwise, wiring seemed pretty straight forward, color coded.

So, I remove the old switch, plug in the new one, get all wires connected to test it. Reconnect the battery, nothing. Just like old switch. No starting, and also no power to he helm. Even in the on position everything is dead. So I grab my volt meter. I found that the red line seems to have 12 volts coming in from one lead, but when I connect all the reds together like they were before and to the ignition switch, the voltage drops to about 2 volts. If I turn ignition to “on” the voltage drops to about a half volt, and when key is turned to “start” it goes down to 0 volts.

What might I be missing and where should I look next. Do I have a short? Does this go out to the helm, or motor? If my starter has failed, would it blackout the whole boat? The only thing that works when the battery is on is the tilt/trim switch mounted on the motor, not the helm one.

I’m dying to get out and fish the striper run here in NJ this spring, I’d hate to bring her in for service and lose the whole season. Any suggestions are greatly appreciated, thanks. If you’re local to me (central NJ) and can fix this relatively quickly, I would consider that too.
 
I forgot to mention, I can’t find any blown fuses, and I found 2 large fuses on the outboard, both ok. Are there more? I also double checked that I have plenty of oil in the main tank and the small tank on the motor. But I haven’t tried to test any sensors yet. Seems odd that the whole boat would power down even with new switch.
 
Welcome to the forum.
Make sure battery posts are "sqeaky" clean.....also ground wire where it connects to the motor itself.
 
Battery power to the switch comes from the motor. Via fuses. Via other electrical connections.

Starter motor failure will not affect power to the helm.

 
I saw a video where, on a later motor, the water pressure sensor had rotted out and it shorted helm power. Is that possible? Is there any kind of a short that would kill the helm juice and affect the voltage at the switch that way? Is it possibly a control unit problem?

thanks, really appreciate any help. And to those who have already offered advice, thanks again. I’ll double check ground wire at motor.
 
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