I have a 15.5 Hp Craftsman lawn tractor. It starts fine but when you push the blade lever up to engage the blades the mower dies. Also if you let out on the brake/clutch pedel the mower stops. Note: the blade safety switch is OK and so is the clutch safety switch as is the seat safety switch. Any ideas

How did you test those switches?

I used an ohm meter to check the safety switches. I pulled the conectors off the switches and checked each switch. The clutch/brake switch and the blade switch have 4 prongs. I checked from white to white and black to black on each switch when the white side was complete the black side was open. The seat switch showed open when the switch button was out and complete when the switch button was in.

I still believe it to be one of the switches (maybe the seat switch)... But go over the wiring and look for any bare wires that may be grounding to metal.

Having the same problem with my craftsman lt1000. Have done the same thing. The only ting I noticed was that because the clutch safety switch faces downward in an area that catches a lot of debris, some of this debris had accumulated on the switch and plug. I'm going to waste a little more time perusing this site for possibly more answers, but if I can fix it, I'll let you know what I did.

You can start your own post or we can tag along with this 3 year old post. The seat switch is frequently the first to go but that stops you from starting if not in the seat. You don't need an ohn meter a continuity tester will do. Closed swicthes should read circuit and open switches no circuit.

Hi,
I agree. Obvious seat switch problem! Why you say? Is it not common sense that if you do either of the two things that the mower requires the seat to be occupied, i.e. clutch/brake or blade, that the mower does not "know" the seat is occupied.
Peace,
Clarke

Let's say you you ohm out the switch and it checks good. I've used mulltimeters on jet aircraft for over 20 years, so knowing how to check circuits is not an issue. Say you unplug the switch and try it, and it still does the same thing. Say you jump the switch and it still does the same thing. Say you also checked the clutch and blade safety switches and it still does the same thing. I don't really suppose that common sense is the central issue here, as that has already been covered. Sometimes it's not just the fuse or the breaker.

In a PM you mentioned a possible carb issue. I doubt that this is carb related if it is always killing the engine when you engage the blade. The switch s likely telling the engine not to spin the blade because it thinks you aren't in the seat. Once I had one where the switch was fine but one of the wires had broken. If you swotch is good test the wire for continumity from each end.

Hi,
I agree so far. Two very unusual things I have seen, each limited mostly to certain types of machines.
The first occurred on the Deere L120-130 family and involved a seat switch that used four wires. The rear wiring harness was not properly protected and would get damaged. Switch checked OK and harness did also. Visual inspection revealed the damage.
The other was with a machine with an anti-backfire solenoid on the carb. Seat switch checked fine and harness did also. The solenoid would shut and kill engine from starvation. Culprit was the seat switch because it was too sensitive. Lotta "bald" people running around figuring that one out. Took two eletrical probes and two people to get to the bottom of that one. One probe in the seat circuit, one in the solenoid power circuit.
Just another "little" point to mention. Control can be through the ground as it was on a question I answered a couple of days ago!
Peace,
Clarke