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Author Topic:   Emergency Kill Switch - 1999, 50 HP Evinrude
cindalyn posted 01-25-2008 08:55 PM ET (US)   Profile for cindalyn   Send Email to cindalyn  
I asked this question before but was told to refer to my operating/parts manual. Unfortunately I don't have one yet but suspect someone will be able to help. My local marine dealer didn’t want to stick his neck out because of the wiring changeover explained below.

I want to attach a kill switch which I have already purchased (Sierra MP40970), to a 1999, 50 HP Evinrude. The previous owner replaced a Yamaha motor with the Evinrude and used the old Yamaha wiring harness so the color coding does not correspond to Evinrude's standard.

After studying the information* others sent to me [] and my current starting switch layout I came to the following conclusion and would appreciate feedback:

-The starter switch appears to be wired correctly, the engine starts and stops OK and the accessory position is working OK.

-The back of the switch has 6 terminals and the present color wires are attached:
A Purple
M Black/yellow
R Red
M' Black (Raised post)
S Yellow/Red
C Yellow/Black

From the information* it appears to me that all I have to do is put a normally open switch between the M and M' terminal. When the ‘retainer’ is removed from the kill switch it closes the contacts and connects the M & M' to ground which is the same condition as turning the ignition switch to the OFF position.

My concern is not being able to look at a schematic and confirm that the right color wires are attached to the correct terminals. Since the switch is operating correctly can't I disregard the colors and just reference the switch markings M, M', C etc.?

After reading more posts on this site it also raised the concern about losing the ‘retainer’ (attached to the lanyard) if the operator falls overboard or "Grandpa, what's this" - -- SPLASH -- happens and we're unable to get the motor started.

Rather than relying on a spare ‘retainer’ couldn't a SPST switch be added in series with the kill switch as follows: [KS = Kill Switch, SPST = Single Pole Single Throw Switch]

From ignition switch position M to KS position A
From KS position B to SPST position C
SPST position D to ignition switch position M'
KS position A to TPST position D

NORMAL Setting - [If the SPST switch were kept in the closed position M should go to ground when the ‘retainer’ was pulled and shut off the engine]

KILL SWITCH BY-PASS Setting – [Flip the SPST switch which would disconnect M from ground and allow the motor to start.]

After obtaining another ‘retainer’ the SPST switch would need to be turned back to the NORMAL Setting.

I believe mounting the SPST switch behind the console or other inconspicuous spot would be prudent and of course pointing the switch and its operation out to any passengers would be necessary.

Does this sound right?

jimh posted 01-26-2008 06:49 AM ET (US)     Profile for jimh  Send Email to jimh     
If you wish to install a switch which will permit the safety lanyard to be overridden, install a switch in series with the safety lanyard. When this new switch is closed, the safety lanyard switch will be operational. When this switch is open, the safety lanyard will not affect the engine operation.

The installation you proposed would have the potential to affect other situations in which the ignition switch was trying to cause the engine to stop, such as the OFF position of the switch. That could result in some unintended results.

It is much less complicated and more easily understood by other operators if you just have a spare safety lanyard to replace the one pulled overboard. They are more likely to understand that concept than locating and operating a hidden switch.

seahorse posted 01-26-2008 08:39 AM ET (US)     Profile for seahorse  Send Email to seahorse     

If you decide to put an overide switch in the kill circuit, be advised that the black/yellow wire carries between 250 and 450 volts while the motor is operating. Most marine switches are only rated for 12 volts and someone may get a good shock. In addtion, the high voltage can arc inside the switch and affect the engine running characteristics.

Why not just obtain a 1996 or later Johnson-Evinrude key switch that uses a lanyard clip to physically turn the key to OFF when it is pulled? It is not needed to turn the key back to start and continue boating.

That way there is no extra wiring, switches, or potential electrical problems involved.

Casco Bay Outrage posted 01-26-2008 10:08 AM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
Ron -

Let me be blunt.

Forget the switch, use the lanyard. If it makes you feel better, have a spare lanyard in the electronics box.

Off to Hamilton's (wink wink)


cindalyn posted 01-26-2008 01:13 PM ET (US)     Profile for cindalyn  Send Email to cindalyn     
Thanks for the advice. I think I'll go with the spare lanyard with the thought of going to the new style switch sometime in the future. I must admit, I never gave a thought about the higher voltage! Boy, it sure pays to ask questions.
nnglenn posted 01-26-2008 01:34 PM ET (US)     Profile for nnglenn    
Just go to the key switch find the wire that is HOT on the run,not start has to be hot on run only, put your kill switch in that wire.
sternorama posted 02-01-2008 12:07 PM ET (US)     Profile for sternorama  Send Email to sternorama     
Did you buy the switch yet? I might still have an extra one somewhere...
cindalyn posted 02-01-2008 10:07 PM ET (US)     Profile for cindalyn  Send Email to cindalyn     
I bought a Sierra MP40970 but haven't installed it yet. Still need to get a spare lanyard ir "clip".


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