Clunker,

A diesel does not have an ignition switch. Only a gasoline engine has an ignition (spark) system and thus an ignition switch. A Diesel has what I call a key switch which turns electrical components on and off and energizes the glow plug relay and starter solonoid which connects the starter to the battery. The key switch works in conjunction with a vacuum valve which is connecten to a diaphram in the injection pump to shut off the fuel to stop the engine.

The actual "ignition" of the fuel. whether gasoline or Diesel, is internal to the engine either in the combustion chamber or the pre-combustion chamber.

P E H