John Deere 310D High Idle Speed: Troubleshooting Guide
John Deere 310D high idle speed: troubleshooting guide. If your 310D is idling at 1500 RPM and won’t shut off with the key, you’re dealing with a high idle speed problem rooted in the fuel control system. These two issues are usually connected. Start with the outside mechanical parts first—throttle linkage, return spring, idle stop, and cold start parts. A sticking linkage or weak spring is often the culprit. If those are good, test the shutoff solenoid, key switch, and wiring. If the engine still won’t shut off or idle down, the DB2 injection pump is likely the cause. But before going that deep, rule out diesel runaway—check the turbo and intake for oil. Safety first, then diagnose in order.












