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ContinuousWave: Small Boat Electrical
c.1960 OMC Ignition Switch Wiring
|Author||Topic: c.1960 OMC Ignition Switch Wiring|
posted 07-23-2010 10:45 PM ET (US)
[The author begins by saying that he] just got [a 1968 Evinrude] [but the motor has] no spark. After doing some troubleshooting, [the author goes on to say that he] noticed [the boat] had a three-prong ignition [switch]--which is the wrong one. [Next the author tells us that he] ordered and received an OEM replacement [ignition switch] which [has] five terminals, and the diagram that came with it does not help out much. [W]hen [I] hook up the [ignition switch] the way [I] think it should be, [and] with the [switch] in the OFF position, the rectifier leads and the flywheel will begin to heat up. What is wrong?
posted 07-23-2010 10:59 PM ET (US)
You must not have the switch connected correctly. No one other than you knows how you have it hooked up, so we cannot evaluate the circuit, other than from your description of the unusual heating of the rectifier and flywheel. This is not normal.
I show the typical wiring of an ignition switch on an OMC outboard in
and this is about all the guidance I can offer.
If you want help diagnosing what is wrong with the way you have wired the outboard motor to the ignition switch, give us an accurate and detailed drawing of all the connections and clearly identify them.
posted 07-24-2010 12:05 AM ET (US)
thank you for quick response. I BOUGHT THE IGNITION SWITCH KIT # 386545 which has the following terminals on it (B), (M),(S),(A),(M). the wiring harness has the following wires grey,black,tan, red/white stripe, green, white, red/ green stripe, red, the last three wires are the transmission wires, red/green stripe, light green and blue. is this enough information? if not ill give you the info on how it is hooked up which is clearly wrong.
posted 07-24-2010 09:49 AM ET (US)
The terminal identifiers you give correspond precisely with the identifiers used in the illustration of the article I pointed to above regarding ignition switch wiring.
In an engine wiring harness there are many conductors which are not associated with the ignition switch wiring. As you note, the color of the wire insulation is varied to help identify the purpose of the wire. I have a listing of wire insulation color codes used by OMC which may also be useful for you. See
You have provided no information about how the wiring is current connected according to your own personal plan and in contrast to the recommended circuitry which you felt was incorrect. It is impossible to make any sort of diagnosis of the problem you are having until you provide a clear schematic diagram of your own wiring plan that you have used to connect the ignition switch. In the article I mentioned, the correct wiring for an ignition switch is shown, I do not suspect there are too many alternative wiring implementations which could be used and still result in proper operation. Therefore I would again suggest that perhaps you may want to wire the ignition switch as shown and as recommended.
posted 07-24-2010 05:40 PM ET (US)
my plan for the wiring of the ignition switch is as follows, I have the red wire and the one end of the blocking diode connected to terminal (A) of the ignition switch, the green wire to terminal (B) the white wire to terminal (S) and the black wire to terminal (M). any way I try to wire it there is always power going to the rectifier. I did notice that the wires going to the vacuum switch both have 12 volts, i do not think that is correct. Il continue to post as much info as I can. thanks again.
posted 07-24-2010 05:47 PM ET (US)
You cannot present the wiring in a narrative. Give a detailed schematic diagram that clearly shows the switch, all wires, and what they connect to at each end. Wire colors are not clear identifiers of function.
In an OMC engine there are no wires with insulation of RED with GREEN STRIPE that are associated with the ignition key switch, nor is there a RED wire, a GREEN wire, or a WHITE wire.
posted 07-26-2010 07:29 AM ET (US)
I believe that is was around 1970 or so that OMC changed its wiring colors to what is used today. Prior to then, the wiring colors were as follows:
Green - B+ and ammeter – 10 gauge wire
Depending on the engine model and charging system, power to the keyswitch – “B” terminal - would either be from the green or the brown wire
posted 07-26-2010 08:37 AM ET (US)
I guess 42-years ago they must have been using different colors. Nice that the engine still runs, by the way. The wiring diagram that BRP supplied with the new switch must reference the current wiring color scheme.
posted 07-31-2010 06:15 PM ET (US)
Im trying to draw a picture with my words. the (B) terminal on the ignition switch is connected to a green wire, at the bulkhead connector it turns to violet witch goes to the thermo switch. The (M) terminal on the ignition switch has a black wire and is grounded to the engine block. The (S) terminal on the ignition switch has a white wire witch goes to the exciter side of the starter solenoid. The (A) terminal on the ignition switch goes to a red wire and goes to the battery + side of the starter relay. (A) also has a jumper wire going to the blocking diode then to the transmission 3-wire harness. follows is the continuity of the ignition switch. with key off position terminals (M) and (M) are the only ones that have continuity. key in run position (B) and (A) are the only ones to have continuity. key in start position (B) and (S), (B) and (A), (A) and (S) all have continuity.
posted 08-01-2010 02:22 PM ET (US)
Now I’ll try to draw a word picture for you. It sounds like your wiring is jury-rigged and not all original equipment, so you will need to figure it out or enlist the services of an experienced professional.
Since you did not provide a model number to help us with your motor, here goes:
B – 12 volts from the battery or starter solenoid battery terminal
M – ground
M - “kill wire” from the ignition (if magneto ignition)
C – choke
A or I – switched 12volts to gauges, electric shifting, ( and ignition if battery powered style )
S – to small terminal of starter solenoid to activate it.
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