1991 312-8 with M12S - won't start

[WH 312-8 Fan 9]

I will try to re-cap the situation the best I can. I know it isi hard to troubleshoot electrical circuits with out being there.
I had bought this tractor back in May with out a mower deck. Started and ran fine. The previous owner had someone wire in a secondary ignition switch for whatever reason. That switch ran between the stud coming off the Starter Solenoid (refer to first picture, where my finger is pointing) and connected to the 1/4" spade terminal on the TAN wire that I believe normall goes to the top PTO safety switch (above the ORANGE) - (Refer to second picture)

I was going to leave the second ignition switch in there as it "wasn't hurting anything" But when I went to do tests on my new mower deck, the PTO safeties were killing the motor when I engaged the PTO. Upon further investigation, I could run it by zip-tying the tabs down on the safety switches (I REALLY needed to get the grass cut).

Now that the grass is cut. I want to make this right (Like Mike Holmes "make this right") I took out the second key switch. It only had two wires going to. I am pouring over the 312-8 wiring schematic that is in the back of the manual but am having a hard time visualizing how the starter solenoid is hooked up since I only see three possible studs on the terminal but there seems to be more connections in the drawing. The schematic mentions a purple wire between the  Obviously there is a connection from the positive terminal on the battery to the starter solenoid and across that is the starter solenoid to the starer connection. 
          NOW, the tiny stud pointing front towards the motor has nothing connected to it. I believe it should have either a purple wire or a black wire going to the oil pressure relay 2 inches away.

symptoms:
Like I mentioned earlier, it ALL worked last night. no issues.
Now that I took out this cobbed up "don't steal my tractor" secondary key switch, my motor won't crank over.
When key switch is on RUN
              (this is all with that single TAN wire with the spade terminal in the second picture installed on the empty spade on the upper PTO safety switch (note third picture)
              I have 12.6 V across the battery
             12.6 V across the terminals of the Starter Solenoid
             Voltmeter registers as well

Can anyone help me with that should be coming off of that empty stud on my Starter Solenoid? I read through some posts here about 312-8's that wouldn't start but they were newer with more relays involved than mine has. 

any help is appreciated!
 

[gwest_ca-(File Mod) 11,113]

Download this detailed wiring diagram and see if that helps.

http://www.wheelhorseforum.com/files/file/1045-tractor-1990-312-x-wiring-detailed-492-4509pdf/

It is for 1990 and 1991

Garry

Opps - changed the file name so you need to use this one
http://www.wheelhorseforum.com/files/file/5190-tractor-1991-312-8-wiring-detailed-492-4509pdf/

Just noticed a slight mistake in the starter motor circuit diagram.
They show the starter circuit completed but the solenoid is not energized. It should be energized with the safety switches in the closed state they are illustrated in.

Edited September 19, 2015 by gwest_ca

[WH 312-8 Fan 9]

Thanks Garry,

I downloaded that and put it with the rest. I love PDF manuals.

I did some more digging. I can't see where this plug (refer to picture ONE) occurs on the drawing (refer to picture TWO).

It would appear that in that connector, a black is coming out of the harness, circling around to the far mating connector and coming back in the meet the ORANGE wire and same store for the TAN wire.

From what I'm seeing, ORANGE should meet up with the black through the Oil Pressure relay, not in some connector just before the motor. 

I can't see where BLACK would meet up with the TAN wire in it's running around either. 

I wish I was smarter with all of this electrical stuff. 
 

[gwest_ca-(File Mod) 11,113]

The black wires are ground wires.

The orange powers the electromagnetic coil in the relay. The ground simply completes the circuit. When the coil is energized it pulls the switch contacts so the light blue and purple are connected. That purple then has power which is the missing wire on the small solenoid terminal.

In the Start mode
With the pto OFF power travels from the tan to the purple.
With the clutch pedal down the neutral switch is closed passing power to the light blue.
With the oil level relay closed you should have power in the purple wire to the small solenoid terminal.

Garry

Edited September 19, 2015 by gwest_ca

[WH 312-8 Fan 9]

Ok Garry, 

I will get the multi-meter back in action tomorrow with a fresh set of eyes.  I appreciate it. any thoughts on me missing a wire off of the stud coming out of the front of the Starter Solenoid?
 

[gwest_ca-(File Mod) 11,113]

It has to be a purple wire coming from the low oil relay.

Orange and black to 85 and 86
Light blue goes to 30
Purple goes to 87
No wire on 87a

Garry

Edited September 19, 2015 by gwest_ca