darrels
New member
Sorry if this gets technical...I have been having problems with the PTO (blades) not engaging when I pull out the PTO switch. Sometimes it works. Other times it doesn't. What I've done:
1) replaced the PTO switch as I didn't think it was working when I checked continuity. However, I may have wasted my money on that as the old one worked after I pulled it out.
2) bypassed the seat sensor, to no avail. Put back to normal operating configuration and ruled out that sensor.
3) bypassed the deck position sensor, to no avail. Put back to normal operating configuration and ruled out that sensor.
4) tested to ensure that the mower would not start if the PTO switch is pulled out (it would not), and that the mower will die if the PTO switch is pulled out and I lift my weight from the seat (it died).
5) checked resistance through the electromagnetic clutch. (2.0 Ohms)
6) powered the clutch via a 12v battery charger and the PTO engages every time starting the blades (so based on the resistance reading and this test, I ruled out the clutch)
7) checked voltage at the connector where the wiring harness plugs into the clutch. At times, it read 12v. Other times I get nothing, so no power there intermittently.
8) checked continuity through all 5 relays in the deenergized state, and all passed.
9) checked continuity for all 5 relays in the energized state. 4 of the 5 passed. The PTO relay did not (no continuity on the proper terminals when energized).
10) swapped another working relay onto the PTO relay harness. It failed continuity on the energized terminals. Since I know the relay was working properly on another part of the harness, I ruled out the relay.
11) Based on the wiring diagram, it looks like power should come into that relay on the purple wire (post 30) and exit out on the Purple/white wire (post 87) when in the energized state.
12) I did have a bad battery (factory original died from age and the cold temps over winter). I replaced it, hoping that maybe the old battery wasn't able to always provide 12v to activate the relay. No joy...
So where do I go now? Any advice would be appreciated! I did not try to see if there is power coming into the PTO relay on the purple wire. Does this problem sound like a short somewhere in the wiring harness? Possibly a bad ground somewhere? Everything else on the mower (every control, light, etc. works perfectly).
Thanks for ANY help you can provide. Short of some good suggestions here, I am about to either replace the entire wiring harness or take it to a local mower repair shop. They are not Gravely people, but an electrical problem like this shouldn't require a lot of brand specific knowledge. Thanks again.
By the way, the wiring diagram and continuity diagram are available on www.billspowercenter.com. That is a GREAT site. Many kudos to them!
1) replaced the PTO switch as I didn't think it was working when I checked continuity. However, I may have wasted my money on that as the old one worked after I pulled it out.
2) bypassed the seat sensor, to no avail. Put back to normal operating configuration and ruled out that sensor.
3) bypassed the deck position sensor, to no avail. Put back to normal operating configuration and ruled out that sensor.
4) tested to ensure that the mower would not start if the PTO switch is pulled out (it would not), and that the mower will die if the PTO switch is pulled out and I lift my weight from the seat (it died).
5) checked resistance through the electromagnetic clutch. (2.0 Ohms)
6) powered the clutch via a 12v battery charger and the PTO engages every time starting the blades (so based on the resistance reading and this test, I ruled out the clutch)
7) checked voltage at the connector where the wiring harness plugs into the clutch. At times, it read 12v. Other times I get nothing, so no power there intermittently.
8) checked continuity through all 5 relays in the deenergized state, and all passed.
9) checked continuity for all 5 relays in the energized state. 4 of the 5 passed. The PTO relay did not (no continuity on the proper terminals when energized).
10) swapped another working relay onto the PTO relay harness. It failed continuity on the energized terminals. Since I know the relay was working properly on another part of the harness, I ruled out the relay.
11) Based on the wiring diagram, it looks like power should come into that relay on the purple wire (post 30) and exit out on the Purple/white wire (post 87) when in the energized state.
12) I did have a bad battery (factory original died from age and the cold temps over winter). I replaced it, hoping that maybe the old battery wasn't able to always provide 12v to activate the relay. No joy...
So where do I go now? Any advice would be appreciated! I did not try to see if there is power coming into the PTO relay on the purple wire. Does this problem sound like a short somewhere in the wiring harness? Possibly a bad ground somewhere? Everything else on the mower (every control, light, etc. works perfectly).
Thanks for ANY help you can provide. Short of some good suggestions here, I am about to either replace the entire wiring harness or take it to a local mower repair shop. They are not Gravely people, but an electrical problem like this shouldn't require a lot of brand specific knowledge. Thanks again.
By the way, the wiring diagram and continuity diagram are available on www.billspowercenter.com. That is a GREAT site. Many kudos to them!