I have a 2015 Deere 310L backhoe. When I bought it in 2021, I replaced the batteries, and cleaned up / silicone greased all of the connections. Went to start it in the cold snap here in Mass, and it would not turn over. When I put the key in the "start position", I heard clicking from what I think are two separate relays, but the starter doesn't turn over. There's power to the radio, lights, etc. I have a systems monitor plugged into the ODB2 port, and it showed 11.6 volts. I do keep the batteries on a charger / float when I'm not using it, so 11.6 sounded low. Checked the diagnostics, and it reported a start relay fault. Since the batteries were 5 years old, I took them out, and had them tested. The auto parts place claimed they were bad. Put two new ones in. First turn of the key - nothing. Second turn of the key, it started. This morning, problem is back. Turn the key, hear two relays clicking, but starter won't turn over. Still showing a relay fault. I haven't looked at the service manual yet, but I think there are two relays. One in the cab, and one in the battery box area. I'm guessing it could be a bad relay that actually switches the high current to the starter, a bad connection in that high current system (+ or ground), or a bad starter. When i turn the key, the two relays engage, but maybe the contacts are bad so the circuit does not complete. To check this, I'm going to put a test light on the + going to the starter to insure that when the key gets turned, voltage is applied to the starter. I also thought about using a set of jumper cables to apply 12 volts to the starter + post to see if the starter runs. Or a bad safety switch or corroded connection on the safety system. Any other ideas?
Im not a Deere expert but the ones that are will most likely ask for the serial number if you have it handy. I would think you have a heavy positive direct to the starter. The solenoid is typically the relay in that circuit. Start with the easy things first. Clean all terminals and lugs pos and neg. Verify voltage at the solenoid. Verify Voltage to solenoid when key is turned. Try tapping on the starter.
You stated you silicone greased all the connections. If you are talking die-electric silicone, then just want you to know that it should never be used on those high current connections as it is a non conductor and although it is good to stop corrosion, it stops charging and stops starting. Clean up the connections as was suggested and if you are looking to prevent corrosion, then just spray the connections with Lloyds Moovit or Deep Creep and it will help greatly. Post a picture of your battery box, and maybe we can suggest other things. Mean time at the starter solenoid try jumping power from the Big Red wire on the solenoid to the small "S" terminal of the solenoid. If it does not crank over you have a cable problem or the starter is junk. Simon C
We're back in business. After replacing the batteries, the voltage on the EDC2 port still showed 11.4 volts. That suggested a bad connection somewhere So I started tracing back. The negative battery post connected to the frame underneath the backhoe, which looked clean. I cleaned it anyway. There was then a heavy, braided strap that connected that point to the actual ground on the starter. I somehow got a socket, extension and ratchet on the starter ground nut, backed it off, cleaned up the connection, and retightened. After reconnecting the battery, the voltage on the EDC2 monitor jumped to 12.6 volts, and the backhoe started. Thanks to everyone who offered advice. It's around 6 degrees here with enough wind to drop the wind chill to -21 deg, so having a heated cab to plow is a gift. We just got another 8 inches on top of the 30 already on the ground.
Cleaning all the grounds every so often is very important especially if they are in wet or corrosive atmosphere. Simon C
Just ordered a mectric SS star washer assortment from Amazon for 16 bucks, not expecting very much. Got double sided star washers that seem very heavy duty and it’s 300 series stainless steel. Great for cables and such.