Backhoe Deere 110tlb keeps blowing ignition fuse

[steinec]

I have a 2003 110TLB with 2000 hrs., it's been a great, trouble free machine for 3 years. Several times a year I drop the backhoe and attach a brush hog. The problem started in June when I pulled the pto knob, it blew fuse #5 for the main ignition. A little experimenting revealed as long as I left the pto alone (with a new fuse) the machine seemed to run fine. I noticed the pto switch felt a bit warm and came here for some reading. I put the hoe back on and ordered a pto switch and fuel cutoff solenoid-the research here suggested one of these was the culprit. Replaced them both and used the machine til mid August when the fuse blew while pulling a stump. Now the machine will start and run, but if I use the hydraulics for more than 5 minutes the fuse blows, and pulling the pto switch kills it almost, but not quite, immediately. I think I've got a chafed wire somewhere but don't know where to look. Was hoping someone on the forum has had the same problem and can clue me in on where to look. Does someone have the wiring diagrams so I can use a meter to try and isolate which wire is the culprit ?.

 

[beenthere]

Finding the wire or condition causing the short can be a pain.
I rig up a blown fuse with a couple wire leads soldered in to a 12v bulb. Plug that into the fuse slot and if/when there is a direct short.. the light bulb will light.
Makes poking around moving wires and playing with switch positions much easier and cheaper than blowing a fuse each time the condition happens.
Might work for you.

 

[steinec]

Thanks for the tip, a neat little trick. If I understand correctly, this would tell me for certain there is a short if I install it right after the fuse blows ? A forum member sent me the schematics, very helpful but overwhelming. Near as I can tell off of fuse #5 there are 13 different possibilities on the hot side. Yesterday I dropped the hoe and the removed the bolts on the instrument console for access. I also experimented a bit and found another piece of info-after I pull the pto knob the tach drops off. It's not instant, seems like maybe after 5 seconds or so it starts to waver then drops. I pushed the pto switch back in & tach seemed normal. What I didn't do was leave the pto up long enough to see if the fuse blew again, will try that today. Heck, the two may have nothing to do with each other, but it got me wondering if it might be ground related since that is the only thing common to the pto and the tach up in the console. It sure would help if someone has travelled this road before !

 

[steinec]

Update on troubleshooting. Every wire I could get to has been checked. Everything to/from the engine, harnesses, fuel cutout, etc are all good as are the front grounds & underbody grounds. I abandoned using the brush hog & kept the hoe installed. No issues for 112 hours. I've 'toyed' with the backhoe presence micro-switch and have found that it sticks. I can simulate the failure and blow the fuse if the switch thinks the backhoe is present and the pto switch is pulled, but I remain convinced there's a wire issue. Next-as soon as the weather goes bad I will drop the hoe, right rear tire, and right fender to get to the last areas to check. Much work but I will find the issue and report back so the next guy has an easier time of it.

Meanwhile, about the sticking presence switch, this is not a new issue for the older 110tlb's. Deere even updated the design, think in 2004/5. Has anyone done/gotten a retrofit of the newer presence switch set-up on an older 110tlb ? Here's the 2 designs they have, 2003 (the older one) is the lower left.