key switch trouble shooting.....

0rion

Seaman Apprentice
Joined
May 19, 2008
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40
Ok, this has been a 2 going on 3 year ordeal with the boat. I'm determined to fish out of my boat this year so I decided to work on it again after letting it sit all last year.
Boat is a 95 sea nymph with a 95 50 hp evinrude (E50TLEOD) on it. I've had a no spark condition and can't get it figured out. I pulled the kill switch wire out of the plug to rule out the kill switch. Today I started looking at the key switch and trouble shooting it using the OMC manual.
I ohmed out the switch and was getting exactly the opposite of what the manual said I should have which confused me. I put one lead on the plate side of the kill wire at the engine and checked ohms key off and key on. Manual said I should see low ohms key off and high ohms key on. When I turned the key to "run"the ohms went to zero. I then pulled the key switch and checked it. Everything tested correctly except one test. Key in the run position between terminal "A" and "B" should show continuity but it doesn't. Would that cause a no spark condition? All the other tests worked as they should....just didn't show continuity in "run" when it should've.
 

dew2

Senior Chief Petty Officer
Joined
May 6, 2010
Messages
674
Re: key switch trouble shooting.....

Thats most likly the problem the run position on the switch no contact no spark.When you turn it all the way to start does it turn the motor? if it does get a new keyed switch.
 

Jayrock

Petty Officer 2nd Class
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Dec 19, 2008
Messages
132
Re: key switch trouble shooting.....

ignition wiring  4.jpg

This is what you should be looking at. If you have no continuity between "A" & "B" with the key in the run position, then my guess is the switch "could" be bad. Its easy to find out. Jump the 2 wires and check for spark. DO NOT ATTEMPT TO RUN THE MOTOR LIKE THIS. If you have spark, replace switch. If not look elsewhere, like the kill wire. Black and yellow. Should only show continuity in the "off" position.
 

0rion

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Re: key switch trouble shooting.....

correct.....I have no continuity between A and B in the run position. Could that cause a no spark condition? It'd be pretty sweet if that's what my problem is. I'm on the waiting list at the marina to get it fixed whether I find the issue or not because I just wanna go fishing. New key switch would be much cheaper than a repair bill.

Let me see if I have this right to jump it to test for spark. I would need to make a jumper between A and B then use another jumper to jump from B to S correct? I'm using the pin labels for clarity here but I'd obviously be jumping the wires they go to on the harness. That will still spark without the key switch hooked up correct?
 

0rion

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Re: key switch trouble shooting.....

View attachment 84928

This is what you should be looking at. If you have no continuity between "A" & "B" with the key in the run position, then my guess is the switch "could" be bad. Its easy to find out. Jump the 2 wires and check for spark. DO NOT ATTEMPT TO RUN THE MOTOR LIKE THIS. If you have spark, replace switch. If not look elsewhere, like the kill wire. Black and yellow. Should only show continuity in the "off" position.

I've already checked that kill wire to the best of my limited knowledge......I removed it from the 5 pin amphenol connector altogether back on the motor and still no spark.
 

Jayrock

Petty Officer 2nd Class
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Dec 19, 2008
Messages
132
Re: key switch trouble shooting.....

correct.....I have no continuity between A and B in the run position. Could that cause a no spark condition? It'd be pretty sweet if that's what my problem is. I'm on the waiting list at the marina to get it fixed whether I find the issue or not because I just wanna go fishing. New key switch would be much cheaper than a repair bill.

Let me see if I have this right to jump it to test for spark. I would need to make a jumper between A and B then use another jumper to jump from B to S correct? I'm using the pin labels for clarity here but I'd obviously be jumping the wires they go to on the harness. That will still spark without the key switch hooked up correct?

Yes. no continuity between A and B will cause a no spark situation. Make a jumper for A and B only. Remove all the spark plugs and leads so the motor does not start, Check for spark.Then just turn the key. no need to jum B and S. if you want to go that route, jumping B and S engages the starter. it will take 2 people to do it this way.
 

0rion

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Re: key switch trouble shooting.....

Yes. no continuity between A and B will cause a no spark situation. Make a jumper for A and B only. Remove all the spark plugs and leads so the motor does not start, Then just turn the key. no need to jum B and S. if you want to go that route, jumping B and S engages the starter. it will take 2 people to do it this way.

well.....I went out and made a couple of long jumpers and jumped straight from B to S and still no spark so I'm back at square 1 again.
 

Jayrock

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Messages
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Re: key switch trouble shooting.....

well.....I went out and made a couple of long jumpers and jumped straight from B to S and still no spark so I'm back at square 1 again.

LONG JUMPERS? They should be like 6 inches long. Not to B and S. Jump A and B. Read everything again and slow down. Jump A and B. B and S engages the starter. Maybe you should leave this to the shop.
 

0rion

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Re: key switch trouble shooting.....

Not to B and S. Jump A and B. Read everything again and slow down. Jump A and B. This tells the powerpack the engine is on. B and S engages the starter.

I guess I'm a little confused. I'm trying to verify spark at the plugs so wouldn't I have to jump B to S to to fire the plugs? Anywho, I made a jumper from A to B and then jumped B to S and still no spark. I made a couple of long leads that reach back to the motor that I'm using to jump B to S to turn the motor over since I don't have a helper. I figure this way I can turn the motor over and watch the plugs at the same time.
 

Jayrock

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Messages
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Re: key switch trouble shooting.....

I guess I'm a little confused. I'm trying to verify spark at the plugs so wouldn't I have to jump B to S to to fire the plugs? Anywho, I made a jumper from A to B and then jumped B to S and still no spark. I made a couple of long leads that reach back to the motor that I'm using to jump B to S to turn the motor over since I don't have a helper. I figure this way I can turn the motor over and watch the plugs at the same time.

Check the voltage on terminal B Should be 12v or better. If not, there is your problem. If so, proceed. Do you have a single connector in the back of the key switch or just single connectors for all the terminals? If it a single big connector, make a small jumper wire, connect A and B. now with the jumper in place plug the connector back in. If you are careful this way will work. Hook up the hose and start the engine normally. It will shutoff this way too. If the connectors are single for each terminal then Jump A and B leave the other connectors alone. procced to start the motor on the hose. Check for spark. If you applied ANY voltage to the black and yellow wire at any time you may have fried your powerpack. Dont let any power at all come in contact to this terminal.
 

0rion

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Re: key switch trouble shooting.....

Check the voltage on terminal B Should be 12v or better. If not, there is your problem. If so, proceed. Do you have a single connector in the back of the key switch or just single connectors for all the terminals? If it a single big connector, make a small jumper wire, connect A and B. now with the jumper in place plug the connector back in. If you are careful this way will work. Hook up the hose and start the engine normally. It will shutoff this way too. If the connectors are single for each terminal then Jump A and B leave the other connectors alone. procced to start the motor on the hose. Check for spark. If you applied ANY voltage to the black and yellow wire at any time you may have fried your powerpack. Dont let any power at all come in contact to this terminal.

thanks for your help.....I'm going to wait until tomorrow when it's light out to mess with it anymore. I have seperate connectors for all the terminals. The way I've been looking for spark has been with the plugs plugged into the wires and laid against the block. I don't even have the fuel line hooked up so I'm not trying to start it....just wanting to see some spark. I haven't put any voltage across the kill wire but that still doesn't rule out a faulty powerpack. I was just looking to rule out the kill wire and key switch. I have no way to really check power off the powerpack because I don't have a peak reading meter. If I start buying meters and parts I might as well just let the marina have at it. Last year when I went up to have them work on it there was a 3 month wait and by that time fishing season would pretty much be over and bow season would be starting so I never took it back up there.....they didn't say this year how long the wait was but I'm assuming it's going to be awhile. I was hoping to get lucky and find something simple.
 

Silvertip

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Sep 22, 2003
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28,758
Re: key switch trouble shooting.....

I think you folks have this gent steered the wrong way. The ignition switch on a two stroke is supposed to read continuity between "B" and "A" in the RUN position. That has nothing to do with the ignition and nothing to do with spark. "B" is the +12 volt feed TO the switch. "A" is the accessory feed TO the accessories (the guages). The only terminals on the switch that have to do with the ignition are the two magneto terminals. Those two should show OPEN in the RUN position and CLOSED in the OFF position.

If there is no spark there is a problem with the magneto terminals on the switch, the kill switch, or the wiring between them and the igntion in the engine or the power pack.

+12 volts on the B terminal in any switch position. If not = bad harness or no power into the engine harness from the battery.

No power on the A terminal in the RUN position but power is available on the B terminal, replace the switch.

No power on the S (starter solenoid) terminal in the START position but power on the B terminal = replace the switch.

No power on the C (choke/primer) when the key is in the START/KEY PUSHED but power on the B terminal = replace the switch.

Lastly: If you want to ruin your ohmmeter, DO NOT make resistance checks with power applied. The internal meter battery is used for power.
 

0rion

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Re: key switch trouble shooting.....

I think you folks have this gent steered the wrong way. The ignition switch on a two stroke is supposed to read continuity between "B" and "A" in the RUN position. That has nothing to do with the ignition and nothing to do with spark. "B" is the +12 volt feed TO the switch. "A" is the accessory feed TO the accessories (the guages). The only terminals on the switch that have to do with the ignition are the two magneto terminals. Those two should show OPEN in the RUN position and CLOSED in the OFF position.

If there is no spark there is a problem with the magneto terminals on the switch, the kill switch, or the wiring between them and the igntion in the engine or the power pack.

+12 volts on the B terminal in any switch position. If not = bad harness or no power into the engine harness from the battery.

No power on the A terminal in the RUN position but power is available on the B terminal, replace the switch.

No power on the S (starter solenoid) terminal in the START position but power on the B terminal = replace the switch.

No power on the C (choke/primer) when the key is in the START/KEY PUSHED but power on the B terminal = replace the switch.

Lastly: If you want to ruin your ohmmeter, DO NOT make resistance checks with power applied. The internal meter battery is used for power.

I don't have continuity between A and B in the run position so it looks like the switch needs replaced. If it's not the kill circuit and it's not the key switch it would seem like the powerpack would be the next logical step. I don't have a peak reading meter though so unless I buy one I'm most likely dead in the water as far as things I can do.
 

Silvertip

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Sep 22, 2003
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28,758
Re: key switch trouble shooting.....

No -- the power pack is NOT the next logical step. You need to verify the kill switch is not activated. The simple test is to disconnect it or test with an ohm meter. Remember: when using an ohm meter to test an individual component, one side of the circuit or the other needs to be disconnected or you "may" also be reading resistance of other components. Like the two magneto terminals, the kill switch terminals are closed to kill the engine and open for it to run. If the kill switch is good, then check the wires between it and the power pack to ensure they are not pinched and/or shorted to ground. Try to start the engine with the kill switch disconnected. Lastly, check the connections on the power pack harness. Disconnet and reconnect them several times to burnish the contacts. There is also the possibility that the stator is bad. The stator is what powers the power pack so you want to verify (via your manual diagnostics) that they are either good or bad. Bad coils can also cause no spark but those can also be checked with the ohm meter. It is highly unlikely both coils are bad so having two bad cylinders does not seem as though coils are the problem.
 

0rion

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Re: key switch trouble shooting.....

I pushed the kill switch wire out of the 5 pin amphenol connector on the motor which should've took it completely out of the equation correct? I still didn't have spark. I also checked the kill wire and it's good all the way back to the 5 pin connector (checked it for continuity). I ohmed out the coils and they both ohmed correctly and like you said I'd be surprised if both coils went at the exact same time. Next in the manual is the sensor coil. Like I said, I don't have a peak meter so I'm limited to only ohm and continuity tests. There's an electronic supply place here so I may run up and just see how much a peak reading meter is. I don't mind spending some cash if it'll help me get this fixed....just trying to keep it reasonable.
 

bob johnson

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4,304
Re: key switch trouble shooting.....

just a thought, (because i went through it) if you are checkign for spark...one culprit could be a weak starter motor not turning enough rpms to make spark...but if you have the plugs out of the cylinders, you should be ok.

you really need to be thorough and go step by step...not jumping all over.....

good luck, watching to see what it turns out to be...whish i could help more...but electrical compnents are fuzzy science to me...

luckily i bought some OMC mechanics test instruments....

bob
 

0rion

Seaman Apprentice
Joined
May 19, 2008
Messages
40
Re: key switch trouble shooting.....

just a thought, (because i went through it) if you are checkign for spark...one culprit could be a weak starter motor not turning enough rpms to make spark...but if you have the plugs out of the cylinders, you should be ok.

you really need to be thorough and go step by step...not jumping all over.....

good luck, watching to see what it turns out to be...whish i could help more...but electrical compnents are fuzzy science to me...

luckily i bought some OMC mechanics test instruments....

bob

I've been trying to follow the manual since I got it but that peak meter is really what's been holding me up. That really limits what I can and can't check. Heck, I don't even know what a peak meter is really. My electrical experience is fairly limited and a multimeter has always been plenty for me. I can check voltages, ohms, continuity, and things like that when working around the house or on cars but have never had the need for anything more. I'm waiting on a buddy to get here that's pretty good with electrical stuff and we're going to look it all over and I'm going to run over to the marina and see if they have a switch and meter.
 

wilde1j

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Apr 15, 2002
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5,964
Re: key switch trouble shooting.....

You don't need a DVA adapter (or peak reading) to check an ignition switch. A regular volt/ohm meters is fine.
 

Silvertip

Supreme Mariner
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Sep 22, 2003
Messages
28,758
Re: key switch trouble shooting.....

You don't need a DVA adapter (or peak reading) to check an ignition switch. A regular volt/ohm meters is fine.

He's already checked the switch and is working on the ignition system where a DVA is required.
 
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