JD 318 electrical problem

[Tractors4u]

Last week I used my John Deere 318 to mow the lawn. The next day I started it and it started right up but when I pulled the switch to turn on the headlights the engine died. I looked and all the idiot lights were off as well. It would not do anything. I towed it around to my garage and started diagnosoing the situation. The only thing that stood out was the ignition switch was rusty on the backside and it had been acting up lately, not wanting to shut off and such. I put a new switch in and at the same time checked all the fuses and connections while I had the battery out and the dash partially removed. This afternoon I got it back together and it started right up and then.............I flipped the switch to engage the mower deck and it done the exact same thing. Does anybody have any ideas? I did notice this afternoon that before it started there was a buzzing sound coming from a black box that sits in front of the steering column.

 

[kubmech]

It's been a while so bear with me here. The "black box" is your controller for the operator present/safety start system. If I remember right you have a standard ground from the battery to the frame as well as an engine ground due to the engine being mounted on rubber isolaters. A common problem was to have bad grounds from either location causing wierd symptoms that you are describing. Sometimes to the point of the engine grounding through the choke/throttle cables causing an unbearable amount of heat if either cable was touched. Also a bad PTO electro magnet will cause problems. Check battery connections as well as both grounds and see if that does anything for you. Take a look at the PTO switch connecter also if you have a bad connection or the connector looks melted you may have a PTO electromagnet problem. A quick check of the magnet is if it's drawing more than 5 amps it's probably shorted internally. I believe you have an amp gauge on your tractor take a look at that and see what that is reading if power is magically restored once again.