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1974-B-80

74 B80

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1974-B-80

My b80 has a good battery and selinoid, but the key wont work. I can jump the selinoid but I won't get spark. What could it be?

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squonk

If the switch is bad it probably isn't sending 12 volts to the coil. You will have 12 volts at the solenoid because the battery is hooked directly to it. Then you jump it and send the juice to the starter

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1974-B-80

That's what I was thinking and I just found a wire broken off of the safety switch for the clutch pedal

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gwest_ca

The pto switch and clutch switch are wired in series (from one to the next) and control the starter solenoid only. No safety switch for the ignition on this one. With key in the run and start positions you should have 12 volts at the coil (+) terminal.

 

Garry

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1974-B-80

I thought there was a safety switch. When I had the tractor running I had to push the clutch down and make sure the deck wasn't engaged. There's a safety switch on the deck PTO handle and on the foot clutch pedal on mine

Edited by 1974-B-80

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khyros

Howdy folks

 

I just picked up my old B-80, mowed the grass with it twice, and went to go move it into the garage after cleaning it up after the second time and it won't start.  I don't get the headlights turned on or anything.  Being that it's sat for the past decade without use, I torn all the terminals apart and cleaned them up.  But still no luck.

 

I'm trying to isolate where the problem is, but wiring isn't my strong suit.  From my understanding, the clutch safety switch needs to be engaged, which should complete the circuit, and both wires should be displaying 12V when this is the case.  But then the deck lever needs to not be engaged, which means that the safety switch grounds it out?  Which I guess makes sense because the seat safety switch would work as a by pass when you engage the mower deck. 

 

But this is where I start to get confused as far as what's supposed to have a 12V charge or not.  And more importantly, how to bypass either the safety switch or the ignition switch to test to see if either of those is the problem.  The fact that the lights don't turn on with the key in run bothers me.  If my knowledge is correct, then that means the ignition switch is not receiving its 12V to redistribute.  I also don't understand how the solenoid knows whether to engage the starter or not.

 

 

 

If it helps at all, when I first bypassed the clutch safety switch, the engine was attempting to turn over, but since I was not expecting that, I didn't have the choke up or even the fuel line flowing.  I rectified those and attempted to restart the engine to no avail.

 

 

Thoughts on where to look?

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rmaynard

No headlights would indicate that the problem is not with a safety switch, but somewhere else. But think of the safety switches like this. In order to have 12v, you must have a complete circuit. The circuit starts at the (+) lug of the battery and ends at the (-) lug of the battery. From the (+) of the battery, 12v goes to one side of the solenoid. From there, a smaller 14ga wire goes to one side of the ammeter. From the other side of the ammeter a green wire goes to the B terminal of the ignition switch. When you turn the switch on, the 12v continues it's path to the PTO switch. If the PTO is disengaged, the switch is closed allowing the 12v to continue to the clutch safety switch. With the clutch pressed, the safety switch closes and allows the 12v to continue to small terminal on the solenoid. This terminal connects to the coil that when energized pulls the contacts together to apply power to the starter. The other end of the coil is connected to GROUND, and back to the (-) lug of the battery, completing the circuit.

 

So, first thing to do is check all the GROUNDS. Beginning with the large wire on the (-) post of the battery, then where it connects to the bolt on the engine, then where the solenoid is attached. Do you have a multimeter that you can perform some simple tests?

 

Many times the ammeter or the connections to the back of it are at fault. If it has those 1/4" slip on connectors, they can get corroded and prevent the flow of current. Also, the ammeter itself can fail, in which case you can just take the two wire off the back of the meter and connect them together. So check all connections. They has to be a "break" somewhere for the flow of current to stop.

 

Check out those things and let us know what you find.

 

post-2221-0-09906500-1382807401_thumb.jp

 

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JimmyJam

Thanks Bob for you info... it always helps all of us!!!

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khyros

Thanks for the help guys!  Between this, the wiring diagram, and a volt meter, I ended up finding and "resolving" the issue.  Turns out that both the clutch switch and the ampmeter weren't working.  That, and by messing with all of it, the wire from the ignition to the safety switch wasn't pushed all the way in and making contact with the ignition switch.  *sigh* Three issues at once sure does complicate things.

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JimmyJam

khyros: I feel your pain and frustration! I was faced with a similar situation! ....but with the help and knowledge from these members of this forum: RED SQUARE, I worked it out!!!!

THANKS GUYS!!!!! You're awesome!!!!! Glad to be a member!

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vickij37
On 9/29/2013 at 5:03 PM, 1974-B-80 said:

My b80 has a good battery and selinoid, but the key wont work. I can jump the selinoid but I won't get spark. What could it be?

try new key switch that ws our problm and it fixed it 

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