JD 755 Starting Problem

[skreis]

Hi all,

I'm new to the forums and have come mainly seeking wisdom regarding a problem that I'm having with a new to me 755.

I've used the tractor approximately 10 hours or so since I purchased it in the winter and as of yesterday, after running it for about 2 hours, can't start it. The parking brake is engaged, the PTO is disengaged, and it's in neutral.

When I turn the ignition, the battery & temperature indicators light up, but the starter does absolutely nothing. The voltage under load looks good, but that's about as far as I've gotten in the diagnosis. I'm not too familiar with testing the starter inhibitor switches, but I did test out continuity of the one that exists under the seat which seemed OK.

I also came across a post on another forum about testing the control/trigger wire connected to the starter (which I believe is the wire that just clips into the bottom of the starter motor?). I think I did this properly, but didn't get any voltage (which I assume means that there is something open in the control wire).

Would it be worth trying to short the starter? If so, what is a safe way to do that?

Thanks in advance - any help is appreciated!

Steve

 

[art]

A year or so ago we had one in that was acting simuliar to yours. Under the center post below your steering wheel we found a little 2x2" square box that all the wires came into for your starting system from the safety switches. It was loaded with dirt and crud and had a soft cover that came off easily. We cleaned it although we knew that was the problem as it started 98% of the time the first time after cleaning but the part is not available through JD and Yanmar never used it.

 

[skreis]

Thanks art, I'll give that a shot and post my results.

 

[dqdave1]

I would chek all safety switches on unit; seat, pto rear and mid, brake, clutch, etc. Make sure all are functioning correctly. Check all fuses also.

 

[skreis]

I haven't been able to test out the suggestions yet due to a project at work, but I also wanted to pose one further question about something that I'd forgotten about..

I noticed a flasher - a Wagner 552 that was clipped in the wiring harness which was visible with the hood up, which had some hole in the casing and looked quite corroded and possibly rusty inside. I'm sort of curious if anyone knows how this gets used? I'll order one nonetheless.

 

[kebo]

I haven't been able to test out the suggestions yet due to a project at work, but I also wanted to pose one further question about something that I'd forgotten about..

I noticed a flasher - a Wagner 552 that was clipped in the wiring harness which was visible with the hood up, which had some hole in the casing and looked quite corroded and possibly rusty inside. I'm sort of curious if anyone knows how this gets used? I'll order one nonetheless.

Don't have a 755, but I have owned (2) 750's in the past. I believe that the flasher you refer to is the signal flasher for the amber caution lights on the fenders.

If you have a handheld voltmeter (DVM), I would check the wire going to the solenoid to see if it's getting voltage when you turn the ignition key on. You should see about 12 to 13.5VDC on that wire when you turn the keyswitch on to spin the starter. If that voltage is present, then there is a problem with the solenoid on the starter motor. If you measure something less than 12 volts, then you could have a loose/poor connection in the ignition wiring, a weak battery, corroded battery terminals, poor battery ground, or some other cause. Usually when you have a low voltage condition on the solenoid, you will usually hear the solenoid "click" but there won't be enough voltage or current to make it "slam" hard enough to engage the starter motor.

Or you could take a piece of 12ga wire straight from the (+) terminal on the battery, and touch it to the terminal on the starter solenoid. CAUTION: I think the 755's are negative ground and that a positive voltage does go to the solenoid, make sure of that first! If it engages, then you have a problem getting the 12VDC to the starter solenoid.

There could be any number of things that could cause that. One thing is the safety interlocks that have already been mentioned. Another cause could be loose connector or broken wire from the ignition switch to the solenoid. Another cause could be the ignition switch itself.

From my experience on JD's, I am guessing you have a bad connection somewhere in the wiring, or the battery is going bad. One last thing that comes to mind is the little DC generator on the engine that keeps the battery charged up. It could have gone bad and thus your battery has run itself down (or maybe the fan belt is loose and the generator is not spinning fast enough?)

Good luck and let us know what you find wrong with it.

 

[skreis]

Thanks for all the helpful tips and pointers. I've definitely gotten to know my tractor a lot better

It seems like the neutral start switch has gone bad. A test for continuity was failing so I shorted it, and it fired right up. The next step will be to figure out how to get into the spot where it needs to be replaced. Have any of you needed to replace this? Does it require much disassembly?

Thanks again and have a good evening!