Blowing fuse on Craftsman riding mower after startup

tomplum

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SO the green seat switches are normally open and typically have a little shorting clip in the connector, which pries out. Could be your culprit. I'm too tired to think further tonight...
 
  
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rangerfredbob

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The seat switch was replaced last year I think? it's the normally open type that closes when you sit down, when it went out I replaced it with a piece of flattened Romex until the replacement came, there's no chip in the connector and the seat switch functions (just checked)

The relay isn't shorted I don't think, I jumped 85 and 86 and it clicks, 30 and 87A have continuity sitting idle as it should and 30 and 87 are open normally like they should be and about 85 ohms across the coil. I do have another relay but it's a Cole Herse with a reverse diode (to switch 85 has to be power and 86 ground) and without a schematic I didn't want to try... the Hella relay that's on it is just a resistor...

I took the rear fender off, found the gas tank cracked... it's small, hopefully the plastic welder will fix it... I didn't find anything odd in the seat switch wiring...

I did replace the ignition switch last year with an Amazon special, any possibility of that being an issue? What about the voltage regulator on the engine?
 

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could it be a loose wire, shorting out on the metal somewhere ? that was the problem I had last year ... went thtough 6=7 fuses randomly blowing as I manouvered around.
 

Roadworthy

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On my Craftsman the seat switch is easily removed by turning a quarter turn to the left. It comes right out of the seat. It is actually two switches in one. There is a normally open part that closes when you sit down and a normally closed part that opens when you sit down. The switch could have failed internally or the wiring going to it could have rubbed through. I suspect part of the ignition circuit is wired through the seat switch such that when you get up it opens the ignition circuit. I've never seen a schematic of the thing, though.
 
  
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rangerfredbob

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This is one of the single switch versions, just two wires

I guess I need to look into the whole circuit diagram if I can find one, see what all goes into the fuse... for whatever reason the headlights aren't working, but I haven't paid attention to if they have worked lately... the wife has been doing most of the mowing this summer but got behind... I suppose I should look into the voltage output of the regulator with the engine running too...
 
  
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rangerfredbob

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I'm running out of ideas, there's no chafed wires anywhere that I can see, I've moved them all and it acts the same... it's a component but can't figure out what one!

It's not blowing the fuse right now, so there's that... I think I'm going to order a new seat switch, maybe it isn't working right even though the volt meter says so, it's doing seat switch things... It's the only thing that would kill it when releasing the clutch or engaging the PTO...

On the plus side, while the rear fender was off I plastic welded the crack in the gas tank, should at least slow it down, and I welded the cracks in the fender itself and cleared off the flaked/rusting paint and primered it. Also gave the thing a sponge bath (it's in the shop, I'm not hosing it off...), the handheld sprayer from Harbor Freight is nice to have around for soapy water... mainly have it for finding tire leaks but it has many uses...
 
  
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rangerfredbob

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Thanks, I'll look through it tonight, I should have the seat switch Thursday so I'll give that a go then...
 

jaxs

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The seat switch was replaced last year I think? it's the normally open type that closes when you sit down, when it went out I replaced it with a piece of flattened Romex until the replacement came, there's no chip in the connector and the seat switch functions (just checked)
I don't see how the seat switch could be at fault. It's working otherwise engine wouldn't turn over. Symptoms point to safty switch circuit which seat is part of but it's closed while cranking and is still closed when clutch is released. If I were suspecting a switch rather than a wire,I would suspect clutch switch. To be clear,have you went through all the motions with new fuse in place without starting engine to see if fuse blows same as if engine is running? Have you held clutch down for extended time after engine is running to see if fuse blows?
I'm going on a limb to talk about something I don't really understand but you mentioned voltage regulator earlier. Food for thought. If when you recieve manual,the diagram show's a rectifier would it be accurate to say it could only be for voltage regulation? 75% of alternators failures are because diodes burn out/go to ground. If fuse never blows as long as clutch is held down,that could mean charging system is disabled (I can't imagine why) until clutch is released. I'm not advocating a replacement, #1 suspect is shorted wire,#2 is shorted switch but if you see a way to disconnect charging circuit it's worth a try. I have to say this is one of the most interesting if not most challenging electrical problem I've heard in a while.
 

RANDYT

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@jaxs In this case the seat switch is not part of the start circuit, so doesn't effect starting. Shorted voltage regulator normally blows the fuse as soon as the key is turn on. A short in the wiring could also cause the regulator to put out more amps than the system can handle and blow fuses, but not likely. In this case the voltage regulator would be connected to the key switch since it also involves an amp gauge. The issue could also be heat related meaning that the failed component only shorts when hot. Electric PTO clutches will do that as well as the regulator and fuel solenoid if equipped.
 
 
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