Who knows what the purpose of this solenoid. How can you tell if it gos bad. Why not just the starter solenoid.

Purpose? Start the boat
Boat wont start if it's bad!
Solenoids are generally used when the current exceeds the capability of the circuit, ie. the keyed ignition circuit. The ignition should be able to handle the current to activate the starter, but other devices like the neutral safety switches may not.
Just my guess.
Gary

Thanks Gary

I tried to figure that one out myself. I don't really understand the use of two start solenoids either.

When mine went out it would just "click" like the battery was dead. But with repeated attempts it would finally engage and crank the engine over.
Easy way to test is to jump the two large teminals together with a screwdriver or pliers. Use caution! This bypasses the solenoid and sends power directly to the starter. If it works that way and not with the key it's probably shot. I believe a new one from Merc is about 20-24 bucks.

thanks Iggy

Dont be confused between solenoids and relays.
relays allow you power large currents form a small
source. A solenoid will move something like engaging
the starter gear in to the flywheel then the relay in the starter will kick in and start turning the starter motor.

Scarab105 is right. The "starter slave solenoid" is a relay. The terms seem to be interchangable when it comes to starting circuit. Merc even calls the starter relay a "starter slave solenoid".
Oh well. I still stick to my guess. Anyone got any other ideas, other than to add one more part to fail?
Gary

The slave solenoid (relay) requires less amps
to operate than the starter solenoid.

With all the different sizes of boats out there,
and the different lenghts of wires used,
it's much easier to use a low amperage
relay, than to run heavier wire throughout
the starting circuit.


my.02

jt

You are right about the relay part of this but the solenoid part of this actually moves the starter gear forward to engage it into the flywheel.

Is it possible that it could be weak and not allow the starter to turn as fast as required or even make the battery appear to be dead or it just engages the starter solenoid and the battery takes over from there.