ignition switch test

dstom

Seaman Apprentice
Joined
Nov 22, 2010
Messages
36
I have a 72 100hp Evinrude. (with a Yohnson single lever hydromatic remote control). When I turn the ignition switch, there is complete silence (however, the choke does engage the butterflies). I was going to start the diagnostic testing at the ignition switch. What tests (and results) should I expect before going on to the starter solenoid? If the switch is bad, what test can be done on the solenoid?

Also, I know I need to replace the battery (I will use my truck battery for tests). What specs should I look for in a new battery? Should I get a marine battery instead of an automotive one? Why?

Thanks for any and all advice!:)
 

dstom

Seaman Apprentice
Joined
Nov 22, 2010
Messages
36
Re: ignition switch test

I have a 72 100hp Evinrude. (with a Yohnson single lever hydromatic remote control). When I turn the ignition switch, there is complete silence (however, the choke does engage the butterflies). I was going to start the diagnostic testing at the ignition switch. What tests (and results) should I expect before going on to the starter solenoid? If the switch is bad, what test can be done on the solenoid? ( and what are good results)

Also, I know I need to replace the battery (I will use my truck battery for tests). What specs should I look for in a new battery? Should I get a marine battery instead of an automotive one? Why?

Thanks for any and all advice!:)
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: ignition switch test

First make sure it is in neutral. If it is, then start with your multimeter (you have one, right?). When you turn the key to start, there shoould be battery voltage at one of the two small terminals on the solenoid, and zero volts on the other one, and the solenoid should click. If it does all that, everything is ok up to that point.

If battery voltage on both small terminals, one is not grounded (safety switch, if there is one).

If no battery voltage at either one, you will have to work backward through the control. Check for voltage at white wire on ign switch, check shift switch (white wires)

You say the choke works, so we know the fuse isn't blown.
 

dstom

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Joined
Nov 22, 2010
Messages
36
Re: ignition switch test

Thank you for the very prompt response (and yes, I have a multimeter).

There is no voltage at either of the white wires on the solenoid. I did NOT make any checks where the power lead attaches to the solenoid. Should that have been done?

I think that means it is either in the ignition switch or in the wiring, Any suggestions on testing the switch? For the wiring, can I just perform a continuity test? Also, looking at the seloc wiring diagram, it appears there should be a big junction box between the control and the motor. Any idea where that might be? The biggest run of wiring between the control and the transom is hidden in a Gunnlel.

Thanks again for your advice!
 

Silvertip

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Joined
Sep 22, 2003
Messages
28,771
Re: ignition switch test

In order for the solenoid to work, current must get from the battery, inside the engine, then up the engine harness to the "B" (battery) terminal on the ignition switch. With the switch in the START position, "B" is connected to "S" (solenoid) terminal and current then goes back to the engine via the harness to the solenoid. The problem is somewhere in that path and it doesn't matter where you check but I would check the "B" terminal on the switch. No juice, the problem is between the battery and the switch. If there is juice, then check the "S" terminal. No juice in the START position but juice on the "B" terminal says bad ignition switch. To prove it, jumper the two terminals. If the starter engages the switch is bad. If not, you did not do the checks correctly.
 

Joe Reeves

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Feb 24, 2002
Messages
13,262
Re: ignition switch test

(Temperature Actuated Choke Solenoid Conversion)
(J. Reeves)

Various OMC engines that were manufactured in the later 1960s thru the early 1970s, for example the 1969 55hp Evinrude/Johnson incorporated a dual stage choke solenoid...... easy to identify as they have two wires leading to the solenoid, one purple/white, one purple/yellow.

The purple/yellow is attached at the engine wiring terminal strip to another purple/yellow wire that led to a heat sensor. The initial stage, with the key ON, (purple/yellow), when cold, would keep the choke pulled in half way until the engine warmed up, at which time it would release and open the choke butterfly.

The second stage (purple/white) is attached to another purple/white wire at the engine terminal strip which leads to the choke switch. When the switch was engaged, the choke closed etc.

The problem with this setup is that as the engine got older, the thermostat acted up, water pump became weak, whatever, the heat sensor failed to operate properly and the choke would not release from that half closed position. This would cause the engine to run in a rich fuel mixture condition (flooding, loading up).

The cure to this problem, via a service bulletin from OMC was to remove the solenoid purple/yellow wire from its original location and connect both of the solenoid wires (purple/yellow & purple/white) to the engine wiring harness purple/white wire at the engine terminal strip.

The above change would allow both solenoid wires to be energized when the choke switch is engaged, pulling the choke butterfly in firmly..... and only when the choke switch is engaged.
 

dstom

Seaman Apprentice
Joined
Nov 22, 2010
Messages
36
Re: ignition switch test

I worked on the motor this afternoon. Why is it that everything takes longer in the cold? Anyway, when I got the control box disassembled, I decided to clean the ignition switch tabs before connecting the battery. Connected the battery and there was juice on the "B" lead.Now, imagine my surprise when testing for voltage on the S terminal, and the starter started turning the engine over!! Hopefully the cleanup did the trick. Thanks to all of you for your responses!!!

Now, lets hope for a warm spell next week so I can take it out of the garage and see if it starts on the hose.

Thanks again!
 
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