Ignition System Circuit Interpretation

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GaryDG

Member
Location
Oregon
I have attached a ignition circuit diagram for an ATV and wish to confirm the meaning of the diagram and the testing method.

The ignition switch has 6 connectors marked A,B,C,D,E,F. See attachment,right hand side.

I don't think I am interpreting the circuit correctly.

Key in "off" position there is continuity between E&F, and no continuity elsewhere

Key in "on" position there is continuity between C&D, and no continuity elsewhere

Key in "start" position there is continuity between A&B, and no continuity elsewhere, including C&D

I am not certain what that small two-sided arrow nor the red line between D&E signifies, can you clarify?

Thanks!
 

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GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I read that as indicating that the entire horizontal bar moves between the Off and On positions, shorting C to D in one position and shorting E to F in the other.
The A to B connection is shown as a push button or momentary contact.
The diagram is not explicit in showing that Off and On are maintained position and Start is a spring loaded motion from On, nor does it convey by itself that the C to D connection is opened when switching to Start. (With the Start Diode providing power to the ignition while C and D are open.)
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I am so glad I am out of that business. Having to work with those diagrams sucks.

Are you having a 'no start' problem?

How many wires are there going to the start switch? Does the diagram wiring scheme match the actual wiring on the vehicle?

I did vehicle systems repairs for about 20 years and the diagrams are terrible. They make up their own symbols and there is no industry standard. I had to do tons of reverse engineering.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I read that as indicating that the entire horizontal bar moves between the Off and On positions, shorting C to D in one position and shorting E to F in the other.
The A to B connection is shown as a push button or momentary contact.
The diagram is not explicit in showing that Off and On are maintained position and Start is a spring loaded motion from On, nor does it convey by itself that the C to D connection is opened when switching to Start. (With the Start Diode providing power to the ignition while C and D are open.)

That's how I see it, too. The diagram shows E and F not being used. I wonder if that's true on the ATV.
 

GaryDG

Member
Location
Oregon
Thank you!
That interpretation is consistent with what I thought about continuity.

You comment "The diagram is not explicit in showing that Off and On are maintained position and Start is a spring loaded motion from On" thanks for that too, the switch, physically, is maintained in Off and On but spring loaded in Start, that is .

So the question is if C&D are closed in Start. I guess I could test with a known good switch.

Thanks again!
 

GaryDG

Member
Location
Oregon
Solution

Solution

Thanks again to everyone that responded!

Yes, I had a crank no start issue with my Polaris. Fortunately while testing that ignition switch I found a loose connection of three wires at a post under the hood. I had checked for loose connections but somehow missed that one. I connected and reinstalled the switch and it now works!
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
... Key in "start" position there is continuity between A&B, and no continuity elsewhere, including C&D ...
That's the problem: it's turning the ignition off while the starter motor turns.

...I am not certain what that small two-sided arrow nor the red line between D&E signifies, can you clarify? ...
It indicates a double-make, double-break, double-throw switch.

The C-D contacts are used with an ignition system that relies on battery voltage.
The E-F contacts would be used with a magneto ignition, which needs to be shorted to ground to turn it off.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
That's the problem: it's turning the ignition off while the starter motor turns.

If you look at the rest of the circuit, I think that you will find that the "Start Diode" supplies the ignition while cranking, getting power from the A-B connection. That is the start position powers starter motor and ignition while the On position powers the ignition only.
The diode is doing the job that a different contact configuration within the switch would otherwise do. In some cases (not this one apparently) the Start position also de-energizes some or all of the Accessory circuits to minimize battery drain while starting.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Thanks again to everyone that responded!

Yes, I had a crank no start issue with my Polaris. Fortunately while testing that ignition switch I found a loose connection of three wires at a post under the hood. I had checked for loose connections but somehow missed that one. I connected and reinstalled the switch and it now works!

Good job. I'm glad you found it without spending a bunch of time hunting it down.

Next time, instead of checking for continuity, use a test light and test for voltage. I have found that to be a faster method that results in fewer headaches.
 

kwired

Electron manager
Location
NE Nebraska
That's the problem: it's turning the ignition off while the starter motor turns.


It indicates a double-make, double-break, double-throw switch.

The C-D contacts are used with an ignition system that relies on battery voltage.
The E-F contacts would be used with a magneto ignition, which needs to be shorted to ground to turn it off.
How old or was there ever an ATV with a magneto ignition system? I remember some three wheeled predecessors of today's ATV's from the 60's and 70's that likely did have magneto - but also did not have anything that was battery powered and a pull cord for starting.
 
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