How much resistance should I see in my clutch switch: 312-8 won't start

[Jrblanke 885]

Greetings folks its me again. I have a 1989 312-8 (some of you saw at the big show) that has a bad starter circuit. The question I have is:

 

How many ohms should I see when testing the resistance through the white clutch safety switch? I need to check it again, but if memory serves me correctly, I was seeing 0.26 to 0.49 ohms. It was notably higher than all of the other switches.

 

As a side note, here are the things we checked/noticed when at the show:

1. The first thing we noticed was that the wire harness has been hacked up, so it takes some forensical scientification to figure out what color the wire is supposed to be and where they go.
2. Seat switch and parking brake switch functions properly, however the seat switch light on the dash is lit very dimly.
3. The PTO switch is completely missing. I have not removed the battery and dug down far enough to find where those wires went and seen how it got bypassed.
4. The clutch switch seems to have 20 times more resistance than the other safety switches. I also cannot remember which side of the switch the blue wire connects to.
5. I am suspicious of the starter relay. At the end of the blue wire that connects to the clutch switch I was getting 11.8 volts. Looking at the wire diagram from a 1986 312-8, I believe the voltage from the battery is supposed to come through the starter relay, and then go through the clutch switch. This is the cause of my suspicion.

 

I have put the tractor up for sale on marketplace because I don’t really have/want to spend the time to fix it. But I doubt anyone is going to purchase a mower that is advertised as having a bad starter circuit. So I feel like I should just bite the bullet and figure out what is wrong.

[Pullstart 64,594]

That doesn’t sound like a ton of resistance to me.  Try continuity.  Many meters give an audible beep when the contacts are closed.  If it beeps when depressed, it should be enough to make it work.

[elcamino/wheelhorse 9,360]

Sit down , have a slice or two of pie ,and take another another wack at the problem. 

[Pullstart 64,594]

3 hours ago, elcamino/wheelhorse said:

pie

Some day, I’m gonna try some of that pie and take a stroll on @wallfish’s bike!  

[squonk 42,579]

3 hours ago, elcamino/wheelhorse said:

Sit down , have a slice or two of pie ,and take another another wack at the problem. 

It's was probably all gone before they left!

[953 nut 57,984]

3 hours ago, Jrblanke said:

I was seeing 0.26 to 0.49 ohms. It was notably higher than all of the other switches.

Chances are one of the connections to the wires to and from the clutch switch is corroded or loose.

4 hours ago, Jrblanke said:

I am suspicious of the starter relay. At the end of the blue wire that connects to the clutch switch I was getting 11.8 volts. Looking at the wire diagram from a 1986 312-8, I believe the voltage from the battery is supposed to come through the starter relay, and then go through the clutch switch. This is the cause of my suspicion.

The diagram for the '89 312-8 has a low oil level relay but if your oil level is good that should not come into play. I think the low oil relay is a silver can connected to the wiring harness. To check it out you can use a small jumper between the purple and light blue wires to the relay, if the starter turns over with the clutch down then that is the problem. If  you unplug the wiring connecter from the tractor to the engine with the key on that relay will click if the oil switch is bad and thinks you are low on oil. If the oil level switch is bad you can cut either of the wires going to and then your start circuit will work just fine.

Let us know what you find.

[wallfish 17,504]

50 minutes ago, Pullstart said:

 take a stroll on @wallfish’s bike!  

You really should!!!!! I always encourage people to take it for a ride but unfortunately only a few actually take the opportunity. @Brennanbo was the only taker this year but he's been on it a bunch of times already.

Let's swap rides next year. You know what I wanna take for a ride

[Pullstart 64,594]

1 minute ago, wallfish said:

You really should!!!!! I always encourage people to take it for a ride but unfortunately only a few actually take the opportunity. @Brennanbo was the only taker this year but he's been on it a bunch of times already.

Let's swap rides next year. You know what I wanna take for a ride

I’ll bring a Wheelhorse powered wheelchair for ya!  

[wallfish 17,504]

6 minutes ago, Pullstart said:

I’ll bring a Wheelhorse powered wheelchair for ya!  

Funny! And I'll put the training wheels on the bike for ya too!

Edited June 29, 2022 by wallfish

[richmondred01 2,289]

On 6/28/2022 at 3:33 PM, elcamino/wheelhorse said:

Sit down , have a slice or two of pie ,and take another another wack at the problem. 

Hey Jim when are you going to change your handle to Eldorado?