1998 Baja 180 Islander w/5.7 liter 250 horse. What exactly is the purpose of a "slave solenoid" in the starting circuitry? Where would I find it, is it different from the solenoid on the starter itself? I occasionally get a no-start - nothing when I turn the key but the guages come alive and I can hear a faint clicking from the engine area. Battery tests good. I am replacing the battery cables because they do have quite a bit of corrosion. Any ideas? Could it be the ignition switch itself? Thank you for any of your thoughts.

Follow the yellow/red wire from the starter solenoid up to the slave solenoid. It is usually somewhere near the ignition module area. The purpose is to avoid running large gage wires with associated current all the way to the dash switch. They are $30-35. Replace that one and carry a spare.

I never understood the reason for a slave solenoid either. Why use one solenoid to activate another solenoid?
You say it's there to keep from running large gage wire to the dash, but any solenoid only needs a 12V low amp signal to activate. I can activate a starter solenoid with a piece of 14 or 16 gage wire.

On our race car, we have to run a slave solenoid (a relay in our case) because the ignition switch itself is incapable of reliably passing the 3-4 amps that the starter solenoid requires.

Seems that this may be the case on the boats as well?

Greg

I had the same problem in my Donzi a click, it was the slave soleonoid. Its wasy to rplace so do it. I have no idea what the purpose of it was.

When merc put together their wiring harness, they did not know if the run from the key switch to starter would be 5 ft or 50 ft. Every time you double the length, you need to increase wire size. They also did not know what kind of key switch each boat manufacturer would use.
So to get around this, they just used an extra solenoid.
I wish they would have put as much thought into their other products, like bravos.
BTW, it's probably on the same bracket as the breaker.

On the same subject, I have a '87 Mag Alpha and I just replaced my slave solenoid about 2 weeks ago. It was the original, and it was toast inside. Anyway, I have only used the boat 3x since I replaced it. I replaced it with a Merc solenoid.

Now, it failed again! The ignition switch works but it doesn't energise the starter motor. I can hear the slave *click* *click* - but no turn over of starter. If I jump the terminals of the slave with my remote starter switch (handy tool!), the starter works fine and turns over the motor. I do not have a kill switch, nor are my shift interlocks a problem (it starts with the key 'on' when I jump the slave as described.)

BTW, I have a 3 season old ARCO starter.

Any Thoughts?

-Larry

Early mercruiser with transmissions used a slave as part of neutral safety circuit. It would ground a little terminal to trannie linkage switch.
Jim

Make sure the slave solenoid has a good ground.

hello,,you sound like u are having same problem. starter just clicks?? i even jumped the starter solenoid and starter worked. i thought it was a ign switch, swapped switchs, then someone in here mentioned the slave soleniod. a new one to me, so mine was right next to distributor, bolted to panel with a large push button fuse. good purchased a couple tomorrow. i will post if that solves problem.
good luck.