JD 285 mower deck clutch

[bensallen]

I have a JD 285 lawn tractor. Last year the mower deck started dis-engaging and my troubleshooting led to the charging system and turns out it was the stator. Stator was replaced and that seemed to fix the problem for the most part. The deck would occasionally dis-engage when I first got it back but seemed to settle down as the season progressed. The first time out this year it worked fine but today it started dis-engaging again. The only thing I could notice was that it seemed to do it more often when shifting from reverse to forward when the tractor would make a slight jerk forward. At first it would re-engage immediately by cycling the switch but later it would either not re-engage without two to three tries on the switch or would re-engage and then almost immediately dis-engage again. One time when I was trying to re-engage the deck the mower also seemed to miss and the engine seemed to want to quit. I got through the yard and was doing some troubleshooting and noticed that, with the engine off the switch seemed very "sticky" like it didn't want to turn off. I could hear the clutch clicking in each time I cycled the switch tho. I'm leaning towards a switch going bad. I was wondering if there is a relay between the switch and the deck and if so where it was. Also if anyone knows of a good source for a shop manual, hopefully cheaper than the dealer, please let me know.
Thanks

 

[Zebrafive]

The PTO system does have a relay. That relay is power thru the ignition relay. The ignition relay is switched "ON" by the seat switch. If the seat switch "opens" the ignition relay "opens" and the PTO relay then "opens" and the PTO clutch disengages.

I would start with the seat switch. A momentary drop of the seat switch current to the ignition relay might not kill the engine, (it might drop/restart and you may not notice) but will drop the PTO clutch. Requiring the PTO switch to be turned off then back on.

If not the seat switch, next check the PTO relay. Look for a group of three relays forward of the battery. Left is coolant temp lamp, middle is PTO, right is ignition.

 

[bensallen]

The PTO system does have a relay. That relay is power thru the ignition relay. The ignition relay is switched "ON" by the seat switch. If the seat switch "opens" the ignition relay "opens" and the PTO relay then "opens" and the PTO clutch disengages.

I would start with the seat switch. A momentary drop of the seat switch current to the ignition relay might not kill the engine, (it might drop/restart and you may not notice) but will drop the PTO clutch. Requiring the PTO switch to be turned off then back on.

If not the seat switch, next check the PTO relay. Look for a group of three relays forward of the battery. Left is coolant temp lamp, middle is PTO, right is ignition.

Seat switch is bypassed. I replaced the PTO switch and it seems to have corrected the problem.

 

[bensallen]

Update on this issue. The mower deck switch seemed to work fine for a couple of trips across the yard however today the deck shut off and when I cycled the switch it briefly kicked in and then nothing since. I looked for the relays you described but didn't find anything forward of the battery. There's a mess of wiring underneath the battery tray so when I get time I'll pull the battery and tray and see if they're under there unless someone can point me to them. Wish I could find a good schematic of that part of the system.

 

[beenthere]

bensallen
You can look at the relay and how it is mounted behind the instrument panel (part # AT75769 ) by going to jdparts.com (free registration) and putting in the model # (285) then RELAY under alphabetical listing.

 

[Zebrafive]

From JDparts

 

[bensallen]

I have checked voltage to the plug on the clutch and getting almost 12VDC. Checked resistance on the clutch coil (2.8 Ohms) I'll have to line up some feeler gauges and check the air gap as that seems to be the problem.