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How to confirm safety switch works


cmcdonald1's Avatar
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08-24-08, 09:40 AM   #1  
How to confirm safety switch works

I am having a most difficult time with my Sears lawn tractor. I cannot start the tractor with the key, only if I jump it at the silinoid with a screwdriver.
At the beginning of the season starting it was intermittent, and if I jiggled the wires at the inginiton switch it would work, now nothing. I thought it was the ignition switch so I removed it and put it on my neighbors tractor and it worked first turn of the key. Then I thought it was the silinoid so I bought a new one and still nothing. The starter is new as well and I am getting voltage everywhere that I am supposed to.

I think now that it could be the clutch safety switch but I do not know how to confirm it. If someone can help me out on this it would be greatly appreciated

Thanks
Cyril

 
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08-24-08, 09:46 AM   #2  
Please post the model and serial number off your mower.

Just because the switch worked in your neighbors unit does not mean there is not a problem with it, these switches all look the same on the outside, but internally the connections can be different, putting the wrong switch on a tractor can wreak havoc on the electrical system, so be sure they are the same before installing them in your or any other mower.

How many wires are connected to your starter solenoid?

 
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08-24-08, 09:48 AM   #3  
Posted By: 30yearTech Please post the model and serial number off your mower.

Just because the switch worked in your neighbors unit does not mean there is not a problem with it, these switches all look the same on the outside, but internally the connections can be different, putting the wrong switch on a tractor can wreak havoc on the electrical system, so be sure they are the same before installing them in your or any other mower.

How many wires are connected to your starter solenoid?
Two that are on the bolts (red and redlarger wires) and two slip on type at the top of the solenoid of which one appears to be a double wire. The model number is SEARS 944.607033 ser# is 0710978001264


Last edited by cmcdonald1; 08-24-08 at 09:51 AM. Reason: update
 
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08-24-08, 09:57 AM   #4  
The two slip on types are the ones you need to be concerned with to determine if the safety interlock is working properly.

The white wire should have 12 volts when the key is in the start position, with the blades disengaged and the clutch/brake pedal depressed. Check the black wires for continutiy to ground, again with the blades disengaged and the clutch /brake switch depressed.

Post back your findings and we can proceed from there.

 
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08-24-08, 10:06 AM   #5  
OK, when I touch the two posts on the solenoid, I see 12 volts. When I place the red wire from my meter on the white wire on top of the solenoid and the black wire grounded to the chasis, there is nothing.

When checking the ohms from the black wire to ground it is fine

 
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08-24-08, 10:27 AM   #6  
I can't find your unit in the Sears parts lookup, are you sure you have the correct model number posted?

The problem appears to be in the circuit with the white wire. I am winging the following without the parts info with the model number.

First thing to do is locate the fuse in your system and test it, to be sure current is getting through the fuse.

Step 2: check your starter switch, you should have 12 volts going to one of the terminal, usually one marked with the letter "B" and usually is connected by a red wire. Check for 12 volts coming out of the switch at one of the terminals when the key is in the start position (terminal usually marked with an "S") and usually will have the white wire connected to it.

Step 3: if all the above checks out, then follow the white wire to the first interlock switch, I think this will be the clutch switch, test for voltage in and out of this switch (remember the key must be in the start position when testing) If this switch tests good, follow the wire to the blade switch and repeat the test. IF voltage fails to pass through either of these switches then this is where your problem lies, replace the defective switch and that should take care of your problem.

Best of Luck...

Post back if you have any more questions.

 
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08-24-08, 10:40 AM   #7  
Posted By: 30yearTech I can't find your unit in the Sears parts lookup, are you sure you have the correct model number posted?

The problem appears to be in the circuit with the white wire. I am winging the following without the parts info with the model number.

First thing to do is locate the fuse in your system and test it, to be sure current is getting through the fuse.

Step 2: check your starter switch, you should have 12 volts going to one of the terminal, usually one marked with the letter "B" and usually is connected by a red wire. Check for 12 volts coming out of the switch at one of the terminals when the key is in the start position (terminal usually marked with an "S") and usually will have the white wire connected to it.

Step 3: if all the above checks out, then follow the white wire to the first interlock switch, I think this will be the clutch switch, test for voltage in and out of this switch (remember the key must be in the start position when testing) If this switch tests good, follow the wire to the blade switch and repeat the test. IF voltage fails to pass through either of these switches then this is where your problem lies, replace the defective switch and that should take care of your problem.

Best of Luck...

Post back if you have any more questions.
That is the correct model number but the serial number was wrong (the 8 should have been a B)

I am not seeing any voltage at the clutch safety switch (2 white wires)

 
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08-24-08, 11:18 AM   #8  
Posted By: cmcdonald1 That is the correct model number but the serial number was wrong (the 8 should have been a B)

I am not seeing any voltage at the clutch safety switch (2 white wires)
No voltage at either wire? did you trace the wire down from the switch to determine that this is the first safety switch down from the ignition switch?? Test the blade switch to be sure there is no power there as well, just want to make sure where the problem originates.

If this is the first safety switch inline from the key switch, then the wire coming from the key switch is either broken or not delivering power from the switch.

 
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