Safety Switch Issue

[953 nut 66,673]

1 hour ago, BHpa said:

connect the two posts of the solenoid (bridging them with a screw driver)

That tells you the cable from the solenoid to the starter is not the problem.

[BHpa 10]

1 hour ago, 953 nut said:

That tells you the cable from the solenoid to the starter is not the problem.

Do you think this would also eliminate any issue with the PTO switch, since it starts to crank?  I would assume if the PTO switch/sensor or whatever was bad to keep it from cranking it would also prevent it in this scenario too, right?  

[Handy Don 16,760]

22 minutes ago, BHpa said:

Do you think this would also eliminate any issue with the PTO switch, since it starts to crank?  I would assume if the PTO switch/sensor or whatever was bad to keep it from cranking it would also prevent it in this scenario too, right?  

No. By jumping the solenoid terminals you circumvented ALL of the safety switches. It tells you only that once the starting circuit is correct, there is power at the solenoid to crank the engine. 

Note that getting the engine to crank and having the ignition to keep it running are two different circuits. 

[Razorback 1,355]

My C160's safety circuit is simple compared to your newer Horse, but when I first encountered my C160 it didn't want to start reliably. It boiled down to the safety switch at the PTO lever not getting engaged when the lever was in the OFF position. After getting awesome help from this site's participants along with a wiring diagram for my tractor, it was just a process of elimination going through the safety circuit using a multimeter. If you don't have one of those, I would highly suggest you get one and learn to use it. A simple continuity test will get you on the correct path. 

 

Keep at it...... you'll get it!

[953 nut 66,673]

On 5/30/2026 at 12:41 PM, BHpa said:

jump the orange and black wires together through the housing but it didn't make any difference - still nothing.  I'm not entirely sure it made a good connection, but I think so. 

The BLACK and ORANGE seat switch wires being joined together with the PTO on will prevent the magneto from producing a spark, just like the operator leaving the seat.

On 5/31/2026 at 8:21 PM, 953 nut said:

Place your shift lever in neutral and block the tires so the tractor can't move. Now take a small jumper wire from the battery "+" terminal to the small purple wire on the solenoid. If the starter turns over the solenoid is working.

What was the outcome of performing this test?

[BHpa 10]

14 hours ago, 953 nut said:

The BLACK and ORANGE seat switch wires being joined together with the PTO on will prevent the magneto from producing a spark, just like the operator leaving the seat.

What was the outcome of performing this test?

Unfortunately, I haven't had time for that yet.  I plan on getting back at it on Friday evening - end of the school year stuff for the kids has the evenings booked up.  

[BHpa 10]

On 6/3/2026 at 6:53 PM, 953 nut said:

What was the outcome of performing this test?

Finally got a chance to work through that list of tests. The only one I didn't do was the second to last one about checking the ground because I was a bit confused about the jumpers and terminals.  But I did the final one in testing the ignition switch.  When I tried jumping the terminals that were connected to B and S nothing happened.  Is there a further test to see if the ignition switch is bad or does that likely narrow it down?  

 

Thanks for these tips, it was very helpful. 

[gwest_ca-(File Mod) 12,283]

[953 nut 66,673]

On 5/31/2026 at 8:21 PM, 953 nut said:

Place your shift lever in neutral and block the tires so the tractor can't move. Now take a small jumper wire from the battery "+" terminal to the small purple wire on the solenoid. If the starter turns over the solenoid is working.

Did the starter turn over with this test?

[953 nut 66,673]

              Double posted.

 

Edited June 6 by 953 nut

[BHpa 10]

On 6/6/2026 at 8:24 AM, 953 nut said:

Did the starter turn over with this test?

Sorry, I had missed this one.  Just did it today - I believe so - if I did it right. 

 

I used a small jumper wire to connect the + line from the battery to the terminal on the solenoid that the purple is connected to - this turned the starter over.  HOWEVER (and I'm not sure if this is what you meant) when I used the same jumper from the + terminal to the purple wire itself (disconnected from the solenoid - wire inserted in to plastic clasp end of the purple wire) nothing happened.  Sorry if I'm not understanding it correctly.

[953 nut 66,673]

5 hours ago, BHpa said:

I used a small jumper wire to connect the + line from the battery to the terminal on the solenoid that the purple is connected to - this turned the starter over.

This proves that the solenoid is functioning properly. The purple wire provides a path FROM the ignition switch to the soleniod if;

the 25 Amp Fuse is good,

the Key Switch is in the START position.

the engine oil level is good,

the PTO is not in the operate position, and

The clutch is depressed.

 

[BHpa 10]

So if all that and the others check out, does it seem likely it's the ignition switch?  I'm sorry if I'm asking dumb or obvious questions - I really don't have a lot of experience in all this, just trying to learn as I work through things on my WH.  I do greatly appreciate the advice and help. 

[Handy Don 16,760]

3 hours ago, BHpa said:

So if all that and the others check out, does it seem likely it's the ignition switch?  I'm sorry if I'm asking dumb or obvious questions - I really don't have a lot of experience in all this, just trying to learn as I work through things on my WH.  I do greatly appreciate the advice and help. 

If you’ve followed @953 nut’s sequence and demystification diagram in post #37 with a VOM and found 12V power before and after each and every component (fuse, switch, etc) then a “non-start” is a cosmic mystery.

 

HOWEVER, if the very first place in the sequence where you do not see power is on the S terminal on the ignition switch (while the key is being held in the “start” position, of course) then you can begin to assume a problem with the ignition switch. 

 

I”m assuming here that you have and know how to operate a volt-ohm meter in VDC (volts DC) mode and are connecting the Minus/Gnd/Ground/Black lead to the negative/minus battery terminal and the Plus/Positive/Red lead to each location in the wiring in the sequence shown under the stated conditions (key to start, clutch disengaged, PTO disengaged, oil level OK). Also assuming that you are proceeding sequentially and not trying to jump around making guesses. 

Edited June 8 by Handy Don

[gwest_ca-(File Mod) 12,283]

A simple 12 volt test light is my first weapon of choice with a problem like this. Usually you can probe the wires at the rear of the ignition switch without disturbing the connector. By following the illustration of the rear of the ignition switch using the one two two terminal positions you can identify the circuit you are after. Then just follow the diagram through each component to get to the intended destination.

[BHpa 10]

6 hours ago, Handy Don said:

If you’ve followed @953 nut’s sequence and demystification diagram in post #37 with a VOM and found 12V power before and after each and every component (fuse, switch, etc) then a “non-start” is a cosmic mystery.

 

HOWEVER, if the very first place in the sequence where you do not see power is on the S terminal on the ignition switch (while the key is being held in the “start” position, of course) then you can begin to assume a problem with the ignition switch. 

 

I”m assuming here that you have and know how to operate a volt-ohm meter in VDC (volts DC) mode and are connecting the Minus/Gnd/Ground/Black lead to the negative/minus battery terminal and the Plus/Positive/Red lead to each location in the wiring in the sequence shown under the stated conditions (key to start, clutch disengaged, PTO disengaged, oil level OK). Also assuming that you are proceeding sequentially and not trying to jump around making guesses. 

Yep, I followed his sequence and first place it wouldn't roll over is the ignition switch - however, I'm not confident I did that part correctly.  Since the wires are in the plastic housing on the end that connects to the ignition I couldn't jump them while still attached to the ignition.  So I unhooked them and then tried to jump the two wires he mentioned (B & S) - that's when it wouldn't do anything.  Is this the correct way to do it?  Again, I'm sorry if I'm asking dumb questions. 

 

[BHpa 10]

So just as an update - I got a new ignition switch and put it in.  Still won't turn over.  So I'm assuming this means I need to track down all the wires to each sensor?  

 

Again, thanks to all for the help and suggestions.  

[Handy Don 16,760]

On 6/8/2026 at 5:07 PM, BHpa said:

So I unhooked them and then tried to jump the two wires he mentioned (B & S) - that's when it wouldn't do anything.  Is this the correct way to do it?  Again, I'm sorry if I'm asking dumb questions. 

As you can see from the diagram, pulling the B wire off stops power from the battery getting through the fuse to the ignition switch. 

 

You didn’t include a picture, so I’m assuming that your ignition switch wiring has all of the wires in a “ganged” connector that then simply presses onto the ignition terminals. 
Yeah, this can make troubleshooting harder!

 

One pretty simple option is to pull off the connector, wrap the stripped end of a length of thin insulated wire two turns around the base of each of the B and S switch terminals (taking care to avoid having them touch each other, another terminal, the switch case, or any part of the tractor). Label each wire with the terminal it’s connected to and then put the connector back on (it won’t go all the way but it’ll go far enough to make contact. 

Now you can use your VOM to see what’s happening at each terminal by touching it to the other end of the thin wire connected to the terminal.

You can use the same trick at the other connectors if your VOM probe can’t reach them  

Edited 8 hours ago by Handy Don

[BHpa 10]

1 hour ago, Handy Don said:

You didn’t include a picture, so I’m assuming that your ignition switch wiring has all of the wires in a “ganged” connector that then simply presses onto the ignition terminals. 
Yeah, this can make troubleshooting harder!

Yes, this is exactly the case.  I didn't know what to call it. 

 

Ok.  I'll see if I can do as you suggest.  Forgive my ignorance, but VOM is a multimeter?  

 

Thanks.

[gwest_ca-(File Mod) 12,283]

If you go to the colored wiring diagram I linked you to earlier the rear of the ignition switch is illustrated. The unique one two two of the connector cavities allows one to identify the individual wires without removing the connector from the switch or even knowing what colors the wires are. Your switch may be upside down but the one two two still applies - just rotate the drawing to match your switch position. 

[Handy Don 16,760]

1 hour ago, BHpa said:

Forgive my ignorance, but VOM is a multimeter?  

Apologies for the acronym. Force of habit.

VOM (or DVOM) = (Digital) Volt Ohm Meter