Alright, so if your Landini Super DT110 isn’t starting and the main relays are heating up, you’ve probably got an electrical gremlin somewhere in the starting circuit. First thing I'd check is the battery — make sure it's actually holding a charge and the terminals are clean and tight. A weak battery or crusty connections can cause high resistance, and that’ll make relays run hot and act weird.
Now, if the relays are getting warm or buzzing even when you're not cranking, odds are the relay’s bad or you’ve got a short or ground fault somewhere. Could be a pinched wire, bad insulation, or even a worn switch letting current bleed where it shouldn’t.
Also wouldn’t hurt to check the starter solenoid — if it's pulling too much current or sticking, that’ll overload the relay. Same goes for the key switch; if it's shot inside, it might not be sending clean signal to the relay or starter.
And don’t forget the grounds. These old tractors need solid grounding or everything acts funky. Run a jumper from the battery neg to the engine block just to be sure.
At the end of the day, tracing it with a test light or multimeter and the proper wiring diagram is the only way to be sure — which is why having the OEM manual helps a ton. It’ll show you exactly where things run and what readings you should be getting. Makes chasing these issues way less of a guessing game.
