Cat 307 shutdown issue

[Dave Z]

Any body have any idea what would make a 307 cat excavator shutdown intermittently? It has an "energize to shut off" style solenoid on it and I'm assuming somewhere in the wiring it has some type of timer or relay to shut it off but ive been unable to locate it. It's definitely an electrical issue shutting it down as after it shuts down you can hear the solenoid "click ' and retract, if you hit the key it starts right up and runs fine till it decides to shutdown again. I also assume somewhere it has some type of protection for low oil psi and overheat that would shut it down if needed and possibly this is causing my shutdown problem ? When it runs it has an overheat light on - will come on when the engines cold, coolant is at 100% full, oil pressure is around 40 psi. Ive already ohmed out the 2 wire sensor from the engine to the back side of the guage panel in the cab and it shows around 1/2 an ohm resistance, the other side of the sensor is a black wire which i assume goes to ground, it also shows around 1/2 an ohm resistance. I'm doing alot of guessing though so if any body has any wiring diagrams or other info that would be great. Thanks for anybodys help.
Machine - 307, Engine 4D32,P.I.N. 2PM00768, Serial 00C04134

 

[Nige]

Here's the Electrical Schematic.

 

[007]

Hi Dave,
A lot of modern engine stop solenoids have the timer your searching for in built.
If Niges circuit is absolutely correct you have a engine stop timer shown in the middle of the diagram.
If i am interpreting the diagram correctly only the key switch can enable the stop solenoid.
All of the sensors are monitored and will raise audible and light alarms at the console.
So to be clear the stop solenoid timer relay will pass battery power to the stop solenoid when it sees a lose of power from the key switch.
This means any loose connection from the key switch, or a cracked fuse, or momentary lose of power to that relay will trigger a stop request within the relay.
Regards.