Ok guys. Heres a hard one. I picked up a craftsman lawn tractor model 917272201 with the 25hp Vanguard Engine. The guy told me that the engine will die when engaging the PTO switch, so he plugged the pto into the headlight switch to cut his grass. I assumed the safety switch under the seat was bad, so i replaced it. I discovered he had unplugged the switch under the seat. When i plugged the switch in, i attempted to move forward and the engine shut off. Even when i put a new switch in, it still died when attempting to engage the transmission. I swapped the pto switch and swapped the connector back to the original place its supposed to go. Try to engage the pto, the engine dies. But if i swap it back to the headlight plug and turn the key to the headlights, the pto engages just fine. No bogging ot anything so i know its an electrical problem somewhere. So right now, seat switch is unplugged, and pto is plugged into the headlight plug. Where in the heck do i start? Its a 46 in deck. Pulleys and spindles are fine. No binding.. ideas please!!
Craftsman Model 917272201
AAalsatropine
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The OPR isn't being energized.
In that state, PIN 87A remains grounded and completes the kill circuit when the PTO switch is engaged.
Either you don't have 12V to the relay, relay is bad or connecting plug is bad.
EDIT- read where you say it clicks---
Since you said the OPR clicks, it must be bad. (somehow)
When it clicks, pin 30 is switched to 87 from 87A.
This opens the kill circuit and completes the ground circuit to the electric clutch.
Do the blades try to engage at all when it dies?
That would indicate the relay is actually doing what it should.
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Yes. The blades try to engage, but the motor dies before they fully engage
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Then the relay is working properly. UNLESS there is a piece of metal floating around inside it that keeps pin 87A grounded.
Got an Ohm meter to check the relay? There should NOT be continuity between 87 & 87A. Pin 30 will connect to either, but NOT both at the same time.
Maybe even a "shake test" to see if you can hear something loose???
The only option I see now is that there is a short in the BLACK wire between The D terminal of the PTO Switch and ground.
ANYTHING that grounds the M terminal of the key switch will kill spark.
What happens if you try to engage the blades with the clutch/brake pedal pushed in?
Got an Ohm meter to check the relay? There should NOT be continuity between 87 & 87A. Pin 30 will connect to either, but NOT both at the same time.
Maybe even a "shake test" to see if you can hear something loose???
The only option I see now is that there is a short in the BLACK wire between The D terminal of the PTO Switch and ground.
ANYTHING that grounds the M terminal of the key switch will kill spark.
What happens if you try to engage the blades with the clutch/brake pedal pushed in?
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The black kill wire is grounded somewhere along the harness between the relay, PTO switch and the clutch/brake switch as indicated by the blue trace on the schematic. The PTO switch would be the first place to look, (grounding internally) but you said it was swapped out with another. A different relay does not fix it either.
You may have to trace the black harness wire to each of the switches and relay to isolate the section of the kill wire that is staying grounded. Carefully check inside each connector terminal. Using an ohm meter to check for shorts, touch the 87A terminal of the relay connector plug or the M terminal of the key switch and ground. Remove all the plugs and connectors, including the ignition switch to isolate the black wire section on the harness. There should be no reading on the meter if the kill wire circuit is good. (There may be a high reading coming from the ignition module).
Leaving the ohm meter on the M terminal plug and ground, install the plug on the clutch/brake switch. Then install the PTO plug. Then install the relay at which point you should get a short reading to ground.
Edit: Does the key switch work properly in all positions? Stop, start, and run?
You may have to trace the black harness wire to each of the switches and relay to isolate the section of the kill wire that is staying grounded. Carefully check inside each connector terminal. Using an ohm meter to check for shorts, touch the 87A terminal of the relay connector plug or the M terminal of the key switch and ground. Remove all the plugs and connectors, including the ignition switch to isolate the black wire section on the harness. There should be no reading on the meter if the kill wire circuit is good. (There may be a high reading coming from the ignition module).
Leaving the ohm meter on the M terminal plug and ground, install the plug on the clutch/brake switch. Then install the PTO plug. Then install the relay at which point you should get a short reading to ground.
Edit: Does the key switch work properly in all positions? Stop, start, and run?
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