Need Help with troubleshooting ignition switch on Murray 12.5 HP
- Thread starter MTD
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Well it appears that there is an internal short inside the brake safety switch harness connector . . .
The switch itself functions properly. Testing the harness gives continuity between the incoming and ground leads and it shouldn't be there.
As far as a fix for this, it should be quite easy to attach some spade connectors to the ends of the incoming leads for attachment to the switch. Access to the wires is difficult without removal of frame and tires.
Could you suggest a safe temporary fix for this?
The switch itself functions properly. Testing the harness gives continuity between the incoming and ground leads and it shouldn't be there.
As far as a fix for this, it should be quite easy to attach some spade connectors to the ends of the incoming leads for attachment to the switch. Access to the wires is difficult without removal of frame and tires.
Could you suggest a safe temporary fix for this?
EngineMan
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If you say its in the wiring and not the switch, try taking a wire from Pin 5 (orange) (in) on clutch brake switch, to (orange) (out) on pto switch, that should cut out the main orange feed wire from pto-clutch/brake but would still leave you with safety switch pto and seat. I think I have that right...!
But remember you will have to take out the bad wire if you say its going to ground.
Have you got now, with new ignition switch full battery power out of Pin 5 when you turn to start..?
But remember you will have to take out the bad wire if you say its going to ground.
Have you got now, with new ignition switch full battery power out of Pin 5 when you turn to start..?
After poking around some more I have found an easy way to properly repair the internal short in the switch harness, so rigging up a temp shouldn't be necessary.
I would just like to confirm once more that:
Sitting on the seat should OPEN the ground connection of the yellow wires. Is this correct?
I will repair the bad wires and try and start her up later this evening. I have to be away for a bit shortly but will post back later.
I would just like to confirm once more that:
Sitting on the seat should OPEN the ground connection of the yellow wires. Is this correct?
I will repair the bad wires and try and start her up later this evening. I have to be away for a bit shortly but will post back later.
EngineMan
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By seating on the seat you don't kill the engine....if that is what you are asking then yes.
You can always put two new wire's in from the switch(s) if you feel they are bad.
But if you have power now at Pin 5 when you turn the key to start, there is a way short cut but only if the bad wiring doesn't kill the coil...!
reynoldston
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I see you already have a lot of advice on this but if you are testing the ignition switch you have to remember you have three different types of voltage going to it. DC positive Voltage, AC positive voltage, and negative voltage. each has its own test and does its own thing. #1 Black is negative feed wire, #2 Red DC positive voltage feed wire, #3 white AC positive voltage feed wire, #4 yellow negative turns off mower engine, #5 orange DC positive activates starter solenoid after it go through safety switches, #6 violet DC positive voltage goes to lamps. Its not hard but you just have to think what type of voltage are you looking for and what does it do. A lot of people don't think as the negative as a voyage but it is and it is just as important as the positive side.
EngineMan
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If he has full battery volt's in at Pin 4, but very little out of Pin 5, he got a bad switch.....yes..?
THE ABOVE IS WRONG, IT SHOULD BE PIN 2 AND NOT PIN 4......!
THE ABOVE IS WRONG, IT SHOULD BE PIN 2 AND NOT PIN 4......!
Last edited:
reynoldston
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Ether its the wrong wiring diagram, somethings not wired right or you have the wrong switch. Pin 4 should be negative power when switch is in off position and pin 5 should have full DC voltage when in the starter position. With positive power to the coil module on pin 4 you will destroy the module. After voltage goes through pin five it looks like it through two safety switches before it goes to the starter solenoid. These test should be done with a multi-volt meter so you know what type of voltages you are working with.
I put the new connectors on the seat safety switch wires and still, I'm shorting to ground in both positions.
So I pulled the the two yellow leads loose and checked the one coming from the Magneto (pin 4_ and there is a path to ground somewhere else in the line . . . From the schematic I cannot see any other path to ground so I am at a dead end for the moment.
Unless I'm misreading the schematic, what I see for the yellow wire path starting at pin 4 (magneto) is a NC circuit through all 3 of the safety switches with a SINGLE ground point coming out of the seat switch. Yet, I am reading TWO. NOTE: the ignition switch was NOT connected to the harness for these measurements. If it were, then Pin 4 would normally be shorted to ground.
The switch connector I pulled loose does actually show an internal short. This suggests the possibility that too much current was pulled (but not enough to open the fuse) and caused an internal short. Or, that it was supposed to be that, though that would seem to make no sense- the switch would be useless.
One would also think the fuse rating matched the breakdown current rating for the switches to prevent internal shorting.
So I pulled the the two yellow leads loose and checked the one coming from the Magneto (pin 4_ and there is a path to ground somewhere else in the line . . . From the schematic I cannot see any other path to ground so I am at a dead end for the moment.
Unless I'm misreading the schematic, what I see for the yellow wire path starting at pin 4 (magneto) is a NC circuit through all 3 of the safety switches with a SINGLE ground point coming out of the seat switch. Yet, I am reading TWO. NOTE: the ignition switch was NOT connected to the harness for these measurements. If it were, then Pin 4 would normally be shorted to ground.
The switch connector I pulled loose does actually show an internal short. This suggests the possibility that too much current was pulled (but not enough to open the fuse) and caused an internal short. Or, that it was supposed to be that, though that would seem to make no sense- the switch would be useless.
One would also think the fuse rating matched the breakdown current rating for the switches to prevent internal shorting.
The only voltages I have confirmed on the switch are that there is +12.75 on pin 2, and that there is 0 volts reaching the small org solenoid wire. I still need to check whether there is voltage coming out of the switch at pin 5 ( to differentiate bad switch from bad path to solenoid switch. Up until now I did not have the harness in an accessible place to safely test this. I would like to get the seat safety switch ground issue solved before trying in case there is something (short) that needs to be repaired.