What is the purpose of the two huge relays in my battery selector box ?

[Milacron]

By huge I mean the diameter of a can of tomatoes but taller... one for each engine in the white box dead center in photo, below the two blue/green battery chargers...to left of yellow extension cord. they both look like new including terminal (no corrosion)...at least the parts I can see from peering below the box (which is open at the bottom)

I ask, as of yesterday I press engine start button for port engine (12v71TA) and nothing happens except that big relay clicks. Starter is dead as doornail...no sound whatsoever. Starboard engine starts fine.

1. Transmission in neutral
2. No corrosion on starter terminals
2. Excellent battery voltage (at dock, chargers on)

I suppose the first question is, is that big relay serving as a remote starter solenoid...or is there another solenoid on the starter itself ? (difficult to see the starter area due to it's low position and solid tubing and hoses in the way)

When the start button is pushed, the big relay engages...should there be 24 VDC at the starter terminals ? If there should be 24 VDC but meter shows 0 VDC, what are some possibilities that might be preventing the voltage getting from point A (big relay) to point B (starter) ?

If it matters, this problem is completely out of the blue...no hint of any issues until yesterday...port engine always started like the starboard engine...the instant the start button is pushed...no hesitation at all.

 

[bigbill]

probably a starter solenoid.does it have 2 large terminals with battery cable on them? if so, check the side that comes from the battery for voltage then press the start button and you should have 24v on the other large terminal. if it does not have voltage when pressing the start button it is probably bad.

 

[dsharp]

I can't see what you're talking about but, it sounds like a solenoid that hooks the batteries in parallel while it's cranking. Check the shift levers to see if there is a neutral safety switch. The starters should have a solenoid mounted on the body of the starter that slams the bendix into the flywheel when entergized.

 

[SKYCHENEY]

If it was a Hatteras, you could simply pull out the wiring diagram and you would know exactly what was there and it's function.

 

[dsharp]

On second thought it could be a slave solenoid for the starter solenoid. A parallel would only require 1 solenoid. Sometimes you have to add them for long, high load circuits. It's basically doing the same job as a relay.

 

[Glory]

If the boat is metal, they could be the disconnect point to remove the power, and possibly ground, from the engine when not cranking. Check for power to the relay and on the out terminal when the start circuit is active, if good then check at the starter.
The solenoid should have a small signal wire just like a starter solenoid.

JM

 

[Milacron]

I can't see what you're talking about but, it sounds like a solenoid that hooks the batteries in parallel while it's cranking. Check the shift levers to see if there is a neutral safety switch. The starters should have a solenoid mounted on the body of the starter that slams the bendix into the flywheel when entergized.

re shift levers, there is indeed neutral safety...when not in neutral even the relay does not click. Transmission is definitely in neutral.

 

[dsharp]

If it's clicking it's either low voltage or a lose connection in the starting circuit. Make sure all the ground cables and the metal jumper from the positive post on the solenoid to the lug on the starter are clean and tight. The discs inside the solenoid are bad about pitting and not making connection if the previous owner had been cranking with low voltage. If you take the cables off the starter make sure the nuts under the cable eyes are tight. The solenoids are rebuildable and pretty simple to take apart. You can also get a push button remote start and work your way backwards from the starter. A voltmeter doesn't tell you much because the voltage may be fine until you put a load on it.

 

[captddis]

A lot of Vikings have a dual solenoid that produces 24 volts. I have replaced a number of them.$$$$

 

[krush]

What year and model is your hatteras? Engine type too....it helps for getting help for us to know.