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Author Topic:   OMC Kill Switch Wiring
george nagy posted 09-18-2006 11:24 AM ET (US)   Profile for george nagy   Send Email to george nagy  
I was rewiring a new separate kill switch to my 1994 OMC 140 Johnson. I'm not sure I wired everything OK because the kill switch doesn't operate properly. I should mention that in the process I broke the separate key switch and replaced it with a new one from [after market vendor] Sierra which seems to work fine. However the lugs on the back were slightly different. I wired the kill switch to interrupt the black-with-yellow-stripe wire from the key switch to the motor. When I tested the kill switch it did not stop the engine. When I removed one connection from the kill switch the motor would not turn off with the keyswitch until it was reconnected. What is wrong here?
jimh posted 09-18-2006 01:39 PM ET (US)     Profile for jimh  Send Email to jimh     
According to the information in the REFERENCE section on OMC color code, the black/yellow-stripe conductor is the kill switch conductor. It is grounded to stop the engine.


george nagy posted 09-18-2006 01:47 PM ET (US)     Profile for george nagy  Send Email to george nagy     
Yes yes I know that is were I got the info since my clmer manual isn't that clear. I wonder if that switch is faulty od if the wiring on the keyswitch is wrong. Is there a schematic anywhere to help with the keyswitch wiring?
seahorse posted 09-18-2006 05:08 PM ET (US)     Profile for seahorse  Send Email to seahorse     
First you have to be sure that you have the correct style of key switch, then test it with an ohmmeter.

Your switch should have 2 terminals marked " M ". Usually one is a vertical post on the back of the switch while all the others are a threaded blade shaped terminal.

Use an ohmmeter to make sure that there is continuity between the two " M " terminals with the key OFF, and no continuity when the key is ON or START.

seahorse posted 09-18-2006 05:10 PM ET (US)     Profile for seahorse  Send Email to seahorse     
I forgot to mention that the black ground wire goes to one of the blade terminals marked with an " M " and the black/yellow wire goes to the raised post marked with an " M ". If you don't have the raised area, then the black/yellow goes to the other " M " terminal.
george nagy posted 09-18-2006 05:46 PM ET (US)     Profile for george nagy  Send Email to george nagy     
Let me try to illustrate what I have. The new keyswitch is very similar to the old one except for two terminals labels. The new one has an "I" instead of a "S" and both have a raised female threaded lug to attach the black/yallow wire. The black/yellow wire connects to the back of the keyswitch and then is split by the killswitch lugs (one on either side)and then proceeds to the engine via the wiring harness. Those black wires that attach to the "M" where are they going, where did they come from and how many are there? I think the problem might be here but I'm not sure I know enough yet.
seahorse posted 09-18-2006 06:16 PM ET (US)     Profile for seahorse  Send Email to seahorse     
Both switches should have an " S " for the yellow wire

" I " or " A " is for the purple to the gauges and wiring harness.

" M " (raised) for black/yellow

" M " blade for 1 or 2 ground wires from wiring harness and possibly the "kill switch"

" C " purple/white for choke

" B " red or red/purple for battery

If your switch is not the same as above, you have the wrong one.

george nagy posted 09-22-2006 12:40 PM ET (US)     Profile for george nagy  Send Email to george nagy     
Well, I got it fixed! I connected one black/yellow wire to the "m" terminal on the keyswitch to the killswitch and another black/yellow wire from the harness to that same "m" terminal on the keyswitch. Then I connected the other terminal on the killswitch to the system ground and that fixed everything. I finally sifted through the clymer manual and found a diagram that worked.
jimh posted 12-03-2006 04:53 AM ET (US)     Profile for jimh  Send Email to jimh     
Wiring of a safety lanyard engine cut-off (or Kill Switch) is shown in

Ignition Switch Wiring
by James W. Hebert

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