John Deere compact tractor won't start.

[gsabin]

My 1994 John Deere 770 won't start. The battery may be defective, but I don't know. It won't start with a spare battery either, but I can jump start it with this battery installed. How can I tell if the problem is the battery, the starter, or something else?

 

[DMW]

When you jump start it are you connecting the negative clamp to the battery post or grounding on the tractor frame?

 

[ultrarunner]

Jump start connecting to the existing battery indicates the existing battery is not up to the job.

When I have a questionable battery my steps are charge and load test… the load test will show pass or fail with marginable in between.

 

[bcjmmac]

Neutral trnsmission switch?

 

[kestrelrogers]

Sounds like a voltage drop issue, check for corrosion or loose connections at the battery terminals, ground strap, and starter. if those are clean and tight, your starter solenoid or ignition switch might be acting up.