wheel horse 312 starting

I have a wheel horse 312 with a Kohler magnum 12 motor. It will not start while cranking. I crank and when I let the key return to the run position it will start. I"ve checked the switch with a VOM and it apperars to be functioning properly.

I suspect you have bad contacts or something broken in ign sw,goto link below & look at wiring diag for tractor & ign sw,disconnect dark blue wire from ign sw(#3-magneto)crank eng,if eng fires when cranking problem internal in ign sw.This is a grounding type ign sw,you should only get an ohmmeter reading between sw case,ground treminal & magneto terminal when ign sw in stop/off position,any other position contacts in sw should be open(no ohm reading)
312

It either has the wrong ignition switch or its wired up wrong or its shorting out.
I have recieved mowers that had battery ignition and some one put a magneto ignition type switch on it.
The way to tell the difference is a magneto switch will have one of the post marked M
The battery ignition switch will have one of the post marked I

I'll check which type switch I have tomorrow. If I have the right switch I'd try Joe's suggestion if I can figure out how to get the M wire out of the connector that goes on the switch. Where does that Mag wire exit the motor? It might be easier for me to disconnect it at another place. Thanks for the ideas.

Harvey is talking about IF ign sw was replaced(you didn't say if sw replaced),if ign sw ORIG OEM sw that came with tractor the sw is correct sw for magneto ign,due to fact sw has operated correctly for yrs.

You can locate/disconnect ign kill lead at eng which will probably be a white wire in a multi prong connector that will probably have alt output in it also,you could disconnect there,however disconnecting kill lead at eng is not a good test for ign sw,if you look at wiring diagram you'll see safety sw's & pto sw also connected to kill lead(dark blue)the whole idea is to localize problem to ign sw or safety sw's,with ign sw disconnected this now only leaves safety sw's in ign kill circuit,if you still have problem with ign sw disconnected then problem safety sw's,pto sw or wiring associated with same,if you disconnect kill lead at eng this now takes ign sw & safety sw's out of circuit & proves/isolates nothing.

I don't know a lot about the history of this machine (I just picked it up this week). The last owner used it only to haul a trailer for fire wood. Someone previously got very happy with wire cutters and a few wire nuts and made it run bypassing the safety switches. That being said I did check the swithch and indeed I have a mag type. I got the blue wire out of the connector (not at the switch but at a connector between the switch and motor. The good news it started while cranking, the bad news it wouldn't shut off. Do I have a bad switch? Thanks again for the advice. This site is the greatest and you people are wizzards.

You have to reconnect blue wire to stop eng,when you removed blue wire from connector all you did was disconnect ign module on eng from stop contacts in ign sw proveing there is a problem in ign sw/wiring.

If blue wire is easy to remove from connector remove wire again,DO NOT start eng,disconnect pos(+) cable from battery(this will prevent starter from cranking eng while checking ign sw)connect one lead of ohmmeter to battery neg(-) connect other meter lead to blue wire in opposite side of connector where you removed blue wire,turn ign sw to all position & watch ohmmeter,if you get a 0 ohm reading in ANY position except stop position then something internal broken in ign sw,this is assumeing sw is orig oem sw,If you get a 0 ohm reading on stop contact(M)when sw in start position,then take mod/sn of tractor to local toro dealer & have him look up correct pn sw and buy/have him order for you.

I got a new switch from a mower shop and I still have the no start while cranking issue. They looked it up by model number so I can only assume it is the right part.

If you still have same problem with new ign sw it indicates that in spite of cutup/spliced wires ign kill side of safety sw's is still connected to kill circuit to eng and that possible orig problem still present.You have two choices.

1-get into a full blown troubleshooting job of checking operation of safety sw's & associated wiring for shorts/shorts to chassis.As a quickie check BEFORE disconnecting any sw's/wiring,check seat sw operation with an ohmmeter(connector for sw disconnected from sw),if there is a jumper in seat sw connector remove same,seat sw is start of ign kill circuit for safety sw's,a bad seat sw or jumper in connector for same will send signal to eng nobody sitting on seat,kill eng ign when cranking eng,seat sw functions same way as ign sw in stop/off position,completeing ground to ign kill circuit.

2-if you don't want to be bothered with troubleshooting/flustration of same & can live without safety sw's,then remove blue wire from connector where you did before as it is apparent that connector is after/downstream of safety sw connection into ign kill circuit.Disconnect tractor wiring harness where it connects to eng wiring,with ohmmeter go between blue wire in connector at eng end of tractor wiring harness connector & blue wire you removed from connector & mateing blue wire still in connector,on one of these wires you will get a 0 ohm reading,splice/butt splice a new wire to wire you got 0 ohm reading on long enough to get to ign sw,reconnect tractor wiring harness to eng,at ign sw locate blue wire in plug connector for sw & confirm that it goes to magneto(M)terminal at sw,if it does seperate blue wire from rest of wires in plug as far back as possible & cut,take end of new wire you added to ign module lead & slice/butt splice to short blue wire tail in ign sw connector,this now bypasses all safety sw's in ign kill circuit.

As a followup/test for new ign module wire connection,start eng,then short end of wire at ign sw end to shell of ign sw/any clean sheetmetal/screw heads or eng block till eng stops,this will confirm kill circuit works before connecting wire to ign sw.

Joe, I chose optin #2 (no trouble shooting) When searching for the wire with the 0 ohm reading I get conflicting results. With the switch off the blue wire has 0 ohms with the tan, white, and orange wires. With the switch in the on position only the tan wire has 0 ohms. Does this make any sense? Sorry I haven't had a chance to get at it sooner but other matters were needing my attention. Thanks for your help.