JD 790 Doesn't Start

   / JD 790 Doesn't Start #1  

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May 7, 2022
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Tractor
John Deere 790
Hello; I saw a thread related to this problem from a few years ago, but my issue is slightly different and has me stumped.

I have a 2005 John Deere 790, with few hours (3 cylinder Yanmar diesel.) It has always started and run without issue, but this week, after a few months idle, it won’t turn over. Turning the key to “RUN” or “PREHEAT” results in the normal (I think) clicking of the fuel pump, but nothing happens when the key is turned to ”START”. No click of the starter, no nothing.

Also, for the first time ever, NO dash lights come on. Normally, the brake light would flash, and the battery and oil lights would come on. The headlights and tail lights DO turn on with the light switch when the key is “ON”. Adding to the strangeness, pressing the hazard light switch makes the hazard light relay tick normally, but the lights do not come on and flash.

Things I tried: I installed a new, known good battery. I installed a new ground cable and cleaned the area where it attaches to the battery compartment floor. I temporarily ran an additional jumper from the battery minus terminal to the alternator frame to ensure a good ground. I checked all the fuses in the fuse box near the operator’s left knee. The fusible link in the starter circuit near the starter is intact. Nothing changed the condition.

I did make the engine turn over by jumping across the terminals on the starter, so the starter does work.

I don’t know how the check the interlock switches. For example, the switch under the seat has 4 wires running from it, and I don’t know what all they cover.

Are there some fuses or circuit breakers I am missing? The little fuse box only has 6 active circuits, and that doesn’t seem like many.

Any ideas would be greatly appreciated! Thanks!
 
   / JD 790 Doesn't Start #2  
Sounds to me like a safety switch issue; that's where I'd start at least.

make sure everything is in neutral - move the levers around. Check all of the wires that you see - actually look at them; move them around a bit. I had a seat safety switch wire on my zero turn break apart on me; no idea why as it was not in a spot to catch on anything; think it just got brittle and one day broke.
 

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