Emergency Stop Switch - Suzuki DF70

Electrical and electronic topics for small boats
Beerspitnight
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Emergency Stop Switch - Suzuki DF70

Postby Beerspitnight » Tue Jun 28, 2016 7:35 pm

Hello. I would like replace the worn out emergency stop switch on my SUZUKI DF70. The current stop switch has two wires going to it: a green wire and a gray wire (see image below). The owner's manual for the DF70 shows the two wires that create the circuit for the switch. The wiring diagram is attached below. I looked at the wiring diagram, but can make little sense of it in this context.

The new emergency stop switch is branded as a generic Suzuki stop switch and has four terminal connections, which are marked "M", "M", "I", and "I" (see image below).

Is there a way that I can ascertain which wires from the current stop switch should go to new stop switch terminals?

Perhaps I purchased an incongruent switch for this application?

Thanks in advance for any advice or guidance on this matter.

Brian
Attachments
Screen Shot 2016-06-29 at 5.43.43 AM.png
Screen Shot 2016-06-29 at 5.43.43 AM.png (60.03 KiB) Viewed 2423 times
New Stop Switch.JPG
New Stop Switch.JPG (96.08 KiB) Viewed 2423 times
Old Stop Switch.JPG
Old Stop Switch.JPG (121.19 KiB) Viewed 2423 times
1989 MONTAUK 17

jimh
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Re: Emergency Stop Switch - Suzuki DF70

Postby jimh » Tue Jun 28, 2016 10:46 pm

The wiring diagram shows a single-pole single-throw (SPST) switch for the existing safety lanyard switch. This is a very simple switch. It is either open-circuit or closed circuit. Use a continuity checker to test the switch.

The new switch is unknown to me. Use a continuity checker to test the switch. It might be nothing more than a DPST switch, or a SPST switch with two sets of terminals.

Once you deduce what action the old and new switch have, you can wire the new switch in place of the old switch.

HINT: from looking at the wiring diagram, it appears to me that the old switch makes a connection between the B conductor and the G conductor when it wants to stop the engine. All you have to do is check the new switch to discover what terminals of the new switch are connected when the safety lanyard is not in place. Then wire those terminals to the B and G conductors. I presume that B is black and G is green. It does not matter which terminal of the new switch gets which conductor.

ALSO: the new switch has terminals marked "I" and "M". These markings may give a hint to the function of the switch. Usually the designator "I" is for an ignition switch circuit that has 12-Volts available when the ignition switch is in the RUN or START positions. Usually the designator "M" is a reference to magneto, an old term for the spark generator in an engine; the M circuit was typically switched to ground to kill the engine. On that basis, I can make the following very speculative inferences about that switch:

--the terminals marked with the "M" designator are probably a SPST switch that makes contact when the lanyard IS NOT in place, and

--the terminals marked with the "I" designator are probably a (completely separate) SPST switch that makes contact when the lanyard IS in place.

Again, this is just speculation. You have to test the switch with a continuity checker to discover what sort of arrangement of contacts it has. However, assuming my assumptions are correct, for your application you would use the two M contacts, and you'd connect the G and B wires from the old switch to them. This would connect G to B when the lanyard IS NOT in place, and should stop the engine.

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: Emergency Stop Switch - Suzuki DF70

Postby jimh » Wed Jun 29, 2016 11:07 pm

To check the switch you can use the continuity test function on a low-cost digital voltmeter, like a $10 one from Sears:

Craftsman 8 Function Digital Multimeter

http://www.sears.com/search=craftsman%2 ... =62651:0:0

Beerspitnight
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Re: Emergency Stop Switch - Suzuki DF70

Postby Beerspitnight » Wed Jul 06, 2016 5:08 pm

I checked both the old switch and the new switch and you were correct in your assumptions, Jim.

I was able to replace the switch the other day without much of a problem, save for the 1/2" diameter of the old switch and the 5/8" diameter of the new switch. That difference required me to drill out the backing plate hole in order for the new switch to fit.

Thanks for your help on this.
Brian
1989 MONTAUK 17