So my 2002 CAT 307C (SN BCM00229) has a issue with the monitor in the cab (PN 167-3613). The issue is that the low oil pressure light and alarm stay on after start up. I changed the oil and replaced the sensor and then finally had Milton CAT come out and tell me it was the monitor. A new one is about 1600$ and the service tech didn't really have a solution other than replacing the monitor, and I am wondering if used parts like this are a thing in the heavy equipment world and if so where? Thanks for any help.
Try the parts section of Machinery Trader.? I see 3 results on there but all of them say "call for prices"
Sometimes monitors like that can be repaired. Either take it apart and check the soldering and connections, and obvious burned or swollen components. Or send it to somebody who can.
I've had good experiences w/ these folks, but I have not purchased any electronics. https://www.conequip.com/
The solder joints are the most likely point on circuit boards to require repair on mobile equipment. Washing the board with isopropyl alcohol, then reflowing the joints with a soldering iron with a fine tip and just a little bit of new solder or flux is enough to rejuvenate the joints. If there are any electrolytic capacitors, those should get replaced, but those are fairly uncommon on logic boards (they are typically used in power supply circuits)
Before you go after the monitor, do you know if Milton checked the wiring harness for continuity from the oil sensor? I'm not sure if the Cats digitally monitor oil pressure, but if the sensor is just a idiot-light pressure switch like on a car, then it's possible a wire abrasion is shorting the oil sensor light somewhere.
Have you checked the United Trading & Engineering Services company website? I highly recommend doing so. https://unitedtradingservices.com/