John Deere 770 Won't crank

tekgraphx · Jun 2, 2013

Last week I cut the grass with my 770 then backed it up to a trailer to hook it up and move some brush. I shut down the tractor, got off and hooked up the trailer, and when I got back on the seat it would not turn over. It was in neutral and both the rear and center PTO's were disengaged.

I checked the battery with and it tested fine. I checked the cables as I had a problem with the grounding cable previously and they are fine. When I first turn the key to "on" the idiot lights come on dimly and then brighten up. When I turn the key to "start" the lights go out (as they would if the PTO was engaged or it was in gear). I tried to check each of the kill switches (neutral, both PTO's, and the seat), by disconnecting the lead and plugging a jumper wire into the harness. Still no joy.

Any suggestions or recommendations would be greatly appreciated. The grass is starting to get a little long. My next stop is to call the Deere dealer, but cash is a little tight right now and I would like to avoid that if possible.

Thanks!

Willl · Jun 3, 2013

How did you test your battery ?

Recheck ALL 4 points of your large battery cables connections.

Tx Jim · Jun 3, 2013

Did you check where negative(ground) cable attaches to tractor??

tekgraphx · Jun 6, 2013

Thanks for the suggestions. I was out of town a few days and will give it another look as soon as it stops raining. I had a problem before with the ground cable and just recently replaced it. When this happened I unhooked the tractor end of the ground cable, cleaned the area and the cable with fine grit sandpaper, applied some dielectric grease and bolted it back down tight. I wll recheck all the connections. I have a commercial battery charger/tester and it shows the battery is good, but I may run it down to the auto parts store and have them check if for me just to make sure. I'll post my results. Thanks again.

RoyJackson · Jun 7, 2013

Before cranking, turn the key to the on position and turn your headlights on. If the lights are bright, your battery is probably OK. Then, use jumper cables to your tractor battery and see if it cranks. If it does crank, your battery may be getting tired and just not putting out enough amps under a load. Even if the starter turns the engine, it needs to turn it fast enough for ignition of the fuel.
If the lights are bright and, even with the battery being jumped, it still doesn't crank...well, you may have a bad starter or cable...or your seat switch, PTO switch or neutral safety switch may be be bad.