Hello everyone, Been having a problem starting my Volvo EC140LC excavator (2001) (EC140LCC03630) with Cummins 3.9 litre motor. The fuel cut off solenoid doesn't pull back when I turn on the key but does stay on when manually pulled into the right position. I checked the plug (three cords) and one gets the 24 volts but nothing from the third. Even bought a new solenoid but nothing changed, it doesn't pull but it stays. Before this problem appeared I heard a buzzing sound when I started turned the ignition key which continued for a while and then stopped. After the problem appeared the buzzing sound ended. Do I have a bad relay or what?
Sounds like your coil commander has failed. It is the short harness that has 3 wires connecting to the fuel solenoid and transitions to 2 wires at the main harness. Or at least that's the way they should be. You should have power and ground going to the coil commander from the machine and it has an internal timer that powers the pull in coil on the solenoid then releases that current and only the hold in current continues.
Yeah that's where the problem was. The connection between the fuse from the cab and the relay has been disconnected for some reason and the relay itself is fine and working. I think I need to get power to the relay from somewhere else and then the solenoid will pull just fine. Though I will have to check around the fuse inside the cab for a little more, the fuse itself has also been changed but to no effect.
So the problem has been solved. In the end the only thing that needed fixing was one of the main fuses next to the batteries, it was blown and right when I changed that everything started working. Well, in hindsight it could've been seen just from the fuses from the cabin since nothing from that positive line worked. That line has: Fuel filler pump, room lamp, radio & cassette, beacon, fuel cut-off solenoid, hand lamp. And this line comes directly from battery. Well, I'm glad that everything works now but it was pretty fun solving the issue.