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 | seon
Join Date: Posts: 1 
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2001-10-17 32483
I know that the PTO has to be disengaged and the transmission must be out of gear in order to for the JD 750 compact starter to engage. The battery was low so I charged it. After 45 minutes, I tried starting the tractor, but got nothing! I reconnected the battery charger and tried to start it again, but still nothing. I checked the PTO and transmission postions and both were in the proper place. Is there a fuse or another safety switch that I need to check? Thanks
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| Kenny
Join Date: Mar 2004 Posts: 46 sale creek
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2001-10-17 32488
Seon, You could have a defective safety switch on the transmission neutral switch or pto neutral switch. You might try wiggling the pto lever and transmission lever while attempting to crank the engine. If starter engages while wiggling a lever, the safety switch on that lever is probably bad. Actually you should start by cleaning all battery terminals and cable connections. Including the ground connection at the frame. Do you have front pto for a mid mount mower? That switch also needs to be disengaged for tractor to start. Do dash lights and/ or headlights work? There is a fusible link in the harness near the starter. It is a white wire about 3-4 inches long with a connector on each end. If it burns out, no lights or anything electrical will work. Then there is always the possibility of a defective starter. If you have access to a voltmeter, you might check for voltage at the starter at the small terminal while holding key in crank position. If you have voltage, but it is less than 10 volts you might consider installing a starter relay that will ensure getting full battery voltage to starter solenoid. I have seen several 50 series compacts have this problem due to resistance in the wiring harness. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2001-10-18 32497
Pretty good summary from Kenny. I'll add that safety switches can be tested directly by a meter. The way the safety interlock system on my Ford 1710 works is that engaging the starter switch powers the starter relay. The relay closes, which completes a ground to the starter motor/solenoid (The starter/solenoid is hot at all times except when the battery is disconnected). The two safety switches are in series with the ground-side of the starter relay winding. The relay doesn't get ground if either safety switch is open, which in turn means that the starter/solenoid doesn't get ground. To test the switches on my Ford, I'd disengage the TX and PTO to close the safety switches and use an ohmmeter to check if there is continuity between ground and the starter relay winding. Both sides of the winding should show continuity. An open winding but good safety switches would show continuity on only one side of the winding. The test would be done with the starter switch off. A test to see if the relay winding is getting voltage from the starter switch could be performed by engaging the TX or PTO, which should open its safety switch. The hot side of that switch should show voltage when the starter switch is engaged. This type of testing is a little confusing, because the circuits are ground-side connections. When the switches, and for that matter the relay are working, measuring from the contacts to ground won't show any voltage since there is no load between ground and the contacts. Electrically, they all are the same point. Of course, this is easier to write than to do. Appropriate test points have to be identified from a wiring diagram, and then the points have to be found on the tractor. Keep in mind that the description is for my Ford. Other tractors may have different circuits and would have to be tested differently. ....
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 | Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2001-10-18 32521
Seon;
On the 85 750 I had there was a switch on the seat. You had to be sitting on the seat to start the tractor. Mine had been wired around as you often want to leave the tractor running but I had the wire work loose once and left me fishing for a solution. Also the battery ground location left something to be desired, As is was down on the right hand front it got dirty and rusted easily this left me fishing around once or twice. We finally had to replace the lead. ....
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| seon
Join Date: Posts: 1
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2001-10-20 32557
Thanks to all who answered this post. I cleaned the battery posts, including the ground connection at the frame and the connection at the starter and wha-la it started!! :>). ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2001-10-21 32568
Seon: That's a good result. Glad to hear it. Your battery will probably charge better now as well. I cleaned mine up this summer, which is something that should be done periodically. Diesels are more sensitive to poor battery connections than gas engines because the starter has to spin the engine fast before it will start. Other periodic maintenance that is sometimes forgotten is: General bolt tightness--especially wheel lugs and loader-frame bolts. There's probably other stuff usually done without really thinking about it that is important to keep a tractor running well. I occasionally lift the front wheels with the loader and then inspect the frame for cracked welds. I also took my PTO shafts apart yesterday to grease the shields, collars and pins-shafts. Well, I repacked my trailer wheel-bearings yesterday so I was involved with grease. Sort of got carried away. Greased under the snow blower chute as well and nearly every zirc in sight. ....
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