312-8 Wiring Question

[Fiddlestix 0]

Doent this wire have to become hot a some point..This wire travels from the mag to the mag prong on the switch, then it goes to the bottom pto relay swtch...is the dark blue a ground wire only?? for some reason i cant understand this wire

The Magnum series (if as manufactured) are magneto ignition and as such are shut down or turned off by grounding the mag coil.

Look at the "Spark Circuit" diagram on page 7-29 in the Demystification Guide. See the Dk Blue wire when dashed is not carrying current (the diagram is show when in run mode). When in off mode that dashed line grounds the primary side of coil.

Do not get this confused with battery coil ignition (old K series) where you start and stop the engine by supplying or denying power to the coil. This is a self sustaining magneto and is shut down by grounding the primary of coil.

[Duff 206]

...my VERY bad, as the younger generation would say!

What I failed to disclose in my earlier post was that I rewired my tractors from scratch because the wiring harnesses had been hacked, corroded, and most of the safety switches were toast when I got them. For this reason I ripped out all the old wiring and rewired using only the simplest circuitry possible to still have the basics - on, off, start, charging and lights - to make the machines usable. *Disclaimer: I do not advocate bypassing/eliminating safety switches for all owners. Your own situation, skill level and familiarity/experience with operating equipment should dictate how you proceed.*

All that said, I apologize for the confusion I may have created. I forgot that wires can and sometimes do change colors after passing through connectors and such, and therefore the published wiring diagrams would (should?) be coordinated to the original as-built condition. I'm still a bit confused by the diagram in my manual, though.

All in all, a learning experience and just another reason why I love this place and the discussions that go on here!

Duff :USA:

[Fiddlestix 0]

Doent this wire have to become hot a some point..This wire travels from the mag to the mag prong on the switch, then it goes to the bottom pto relay swtch...is the dark blue a ground wire only?? for some reason i cant understand this wire

Not to keep beating the drum but too much info can't be too bad... could it?

Here Michael,

This is the very first page of the Magnum Service manual Electrical Section. It gives a brief description of the ingition system and some do's and do not's. We wouldn't want you to damage your ignition unit. again, this is a system very opposite in hook up to a battery coil ignition of many older K series (they too were available with magnetos but we've grown to overlook that.

Read the caution paragraph..do NOT connect 12V to the ignition circuit in any manner. Notice the diagram in the lower left shows the module being routed to an ignition switch that eventualy grounds the coil. This prevents interuption of the primary side of coil which in turn prevents collapse of the secondary which ultimately snuffs out the high voltage out the secondary side and thus the spark.

One more question,,,where does the pigtail mount ,,,it looks like it has two screws that hold it somewhere?

Do you mean the plastic connector immediately aft of the engine that contains the kill wire, charge wire, and the two oil level float switch wires? On my '88 310-8, this is simply tied to the engine with an insulated strap of steel type harness holder. The screw ears go unused.

Duff, you've created no confusion... those electrical diagrams of Wheel Horse are what's confusing! On the aforementioned 310-8 for instance, Kohler supplied the engine configured with a Violet B+ wire, a White coil grounding wire (kill), and two Red float switch wires. Once these 4 engine wires went into that connector, they exit as a White charge wire, Dk Blu kill wire, one Tan float wire and one Orange float wire.

This all agrees with the Demystification guide's INDIVIDUAL circuit diagrams, but conflicts with the overall system schematic. It would appear, the individual diagrams are more accurate than the complete system schematic.

I too, hope that I haven't mucked up the waters here. It all gets cornfuzing after awhile!

Does this help any Michael?

[Michael Bullington 5]

man you guys rock with all this information!! I would not be this far without your help...I wish I was more patient....but last nite I burned up the ignition switch Now i understand the dark blue wire!!

Im ordering a new switch, rectifer, and drive belt tonight!

wonder why the heck the PTO has two switches??

[TT-(Moderator) 1,162]

wonder why the heck the PTO has two switches??

One switch allows the starter circuit to work when the PTO lever is in the off position.

The second switch enables the seat switch safety circuit while the PTO is engaged.

[Michael Bullington 5]

that clears that up......thanks TT....now correct me if i wrong i was thinking you had to be sitting on the seat to start the tractor...but if this switch only works when the PTO is operating..that means it will start without me sitting in the seat...would that be a safe assumption?

[TT-(Moderator) 1,162]

The clutch pedal must also be depressed (and parking brake applied & tranz in neutral on some of the newest models), but yes - you can start them without being on the seat.

The seat switch will shut off the engine if the PTO is engaged and the operator leaves the seat - or slides far enough to one side to activate the switch.

[Wheelhorse616 4]

Hey Michael, I own a 1990 Wheelhorse 312-8 and I was wondering if you ever found were that ground off the starter solenoid went to, that's the last part to the project and should be able to get it to run with that. Thanks. TT do you know were it goes, if so, it would be a great help.

Edited November 20, 2021 by Wheelhorse616