1988 John Deere 420 with PTO/Electrical Problem

Tango2020 · May 8, 2014

The battery light comes on after I mow for 20 or 30 minutes. The second I disengage the PTO the light goes off. If I keep mowing with the light on it eventually blows the 20amp fuse located behind the instrement panel and the engine dies. When I replace the fuse the engine will start again and run fine but the mower won't engage when I flip the PTO switch (although the PTO indicator light will illuminate with the switch on). IF I l let the tractor set and cool off we start the process over again. What could be causing this? I assume it's an electronic problem but my mechanic skills are basic at best. Should I change the time delay control module? From what I have read, it is rare for these to go bad. Are there other components I should check or replace? Thanks in advance....

bobmisi · May 8, 2014

When my exmark and my bolens did that it was time for a new PTO clutch. They are not cheap, but whadyah gonna do...............

Tango2020 · May 9, 2014

I'm fairly convinced at this point that is the problem. Thanks for your reply!

David_Kb7uns · May 9, 2014

The clutches on those need to be kept adjusted, the wider the gap the more current goes through the coil and the hotter it runs, used to be able to just get a new magnet, think the current draw should be around 6 amps or less.

David Kb7uns

Tango2020 · May 12, 2014

Thanks David. How are those adjustments made? Is that something I can do or is it better done by the dealer?

ovrszd · May 12, 2014

I wasn't aware they were adjustable either??? Never heard of that. The clutch is simply an AC clutch like what's used on autos. Pretty sure your clutch is the problem. I'll be following this thread to hear the solution.