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Joeyd

312-8 issues

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I have an 89 312-8. Up until this past week I haven't had any problems with it. Last fall I replaced the solenoid, ignition switch, seat switch and fuel lines. I went to go start it the other day to mow the grass and I got nothing. The lights all turned on like normal but it would even turn over. All the test lights worked when i checked them. I checked the usual things like  the pto, clutch, battery, etc. Today, I took the clutch switch off and jumped it with no improvement. Same with the seat switch. I was beginning to think it was maybe the low oil switch but the light wasn't on. Later I jumped the solenoid and got it running with no problem but the clutch light stayed on the entire time and I wasn't able to turn the tractor off with the key. When I turned the key to off, the lights dimmed for a second but everything remained running (I'm assuming that's because I jumped the solenoid). So now I'm thinking it's either the clutch switch or the ignition. Any ideas? Still new to wheel horse. Thanks in advance.

-Joe

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Here are the wiring diagrams.
http://www.wheelhorseforum.com/files/file/1862-tractor-1989-312-8-wiring-detailed-492-4509pdf/

The ignition is self-powered so the ignition wire is simply grounded to shut it off. Not grounded and it will run.
Do not allow any battery power into that ignition wire. It will smoke the ignition coil.

With magneto ignition a safety switch that is jumped can ground the ignition so it will not run.

1/2 of the pto switch controls the starter circuit.
The other 1/2 controls the ignition.

Garry

Edited by gwest_ca

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:WRS:      The clutch safety switch will prevent cranking, since that light was on you may want to check it out.              :text-welcomeconfetti:

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Fellas,

Still at a dead end with my issue. I've troubleshot every switch and they are all working. Anyone think it could be the relay that the clutch runs into where it branches off?

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You will need some help with this.

Try to start the starter. Pto OFF and clutch pedal down. Place your third hand on the low-oil relay and see if it thumps or clicks when the starter circuit is activated by the key switch. If it does the low oil switch in the engine is closed indicating the oil level is low. The oil may not be low and the magnetic switch is loaded with metal particles preventing it from opening. There are special instructions on servicing the switch so read up on them before attempting removal.

Here they are
http://www.wheelhorseforum.com/files/file/2062-wh89-90-t17-oil-level-switch-servicepdf/

Let us know what you find.

What do you have for testing? 12 volt test light? Voltmeter?

Garry

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The low oil relay isn't clicking or anything. Just checked that. Is there a way to by pass the ignition switch to verify that isn't my issue without frying the ignition coil?

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I tapped on the relay and it started to crank while turning the key. I think that relay may be bad. Can I jump that to determine for sure if that's the issue?

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Remove the relay so you can get a good look at the terminals for corrosion and/or overheating. This is how they usually fail. This is how you check the condition of the relay

Do you understand it and can you do it?

Garry
 

Low oil relay.jpg

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Thanks for that. Man do you have a lot of references!! I just fixed it. I was trying to start it earlier and it cranked. I realized it only cranked when the ground of the ignition switch was touching the side of the panel where the panel screws into the tractor. So I did it a couple times and thought it was the ground. So I said screw it and cut the seat switch off and tied them together and grounded it. It works now. Thanks for all the help. Hopefully you guys are this helpful next time. Glad it was something stupid and I learned a lot from this haha. Thanks again

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If you did what I think you did you should not have spark. Whatever you attached the seat switch wires to is not grounded. If it was you would not have spark.

But it runs so we can't knock success.

If it crops up again check all your grounds.

Garry

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I cut the three wires that went to the seat switch and put them all together into butt connector and then ran a wire to a ring wire connector and attached it to one of the bolts that hold the seat bracket onto the tractor. Any other way I should do it?

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The tractor chassis metal is what provides the ground for most circuits. Frame, hood, seat pan and hoodstand metal. When new the bolts that connect everything provide the ground through to the (-) battery cable. I like to see the (-) cable bolted to the engine block because the starter motor is the single largest load the electrical system will ever see. Then another heavy wire from the engine block to the chassis should take care of the rest but in your case there must be enough corrosion between the metal components to defeat the grounding.

Disconnect the seat wires you joined together and separate them so you are back to where you started.
Take a test light and hook the wire lead to the (+) battery post. Touch the (-) post with the probe to verify the light works. Now probe the different metal parts and panels to see if it is grounded.The light should work on each one and if it does not that item is not grounded. Check the base of the starter solenoid - this ground may be the original cause of the no-start condition. There may be a bolt near the right side of the battery tray and below the throttle cable with a few black wires providing grounds. Check that point.

Grounds are 1/2 of every circuit and just as important as the wire powering a circuit.

You can do the same test using a voltmeter. Record the voltage reading across the battery posts - red lead to the (+). Now probe the metal chassis components with the black lead and see what the voltage is. It should be the same. If not the voltage drop is the result of resistance between the bolted together parts or a broken ground wire. Check both ends of that wire and wires.

Let us know what you find.

Garry
 

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The key switch is only grounded by the two screws holding the dash panel. My 312 wouldn't start, I tried jumping it still wouldn't start. I tighten the screws on the dash panel and it started with out the jump. Later I remove them and removed a small amount of rust from them and the corners of the dash panel.
I suggest that you check all the bolts and screws on the hood stand for tightness and rust.
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The ground wire to the ignition switch is there to ensure the key switch will kill the ignition in the OFF position - no other reason.

If the ignition switch needs a ground to make something else work it can only mean the other end of the ground wire is not grounded as it was originally intended. I would call it a minor ground and there is a good chance it is overloaded under these conditions.

Garry

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Posted (edited)

I have a 312-A wheel horse I replaced key switch solenoid and relay still want start by key can start buy jumping lugs on solenoid what could keep me from starting with key. I also jump oil switch it was bad I check oil each time I use it. Some one already jump safety switch to to brake. I know seat switch works. Could pto switch to starting side be bad and how can I check. 

Edited by lastoja

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Try taking the jumper off the low oil switch. I think that is your problem. Just unplug the oil switch wires.

 

Garry

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