102C3 'door open' light stays on and fuel filter question

[ChuckMC8]

Hi All,
I'm doing some maintenance on our church bus, its a 93 102C3 with a 3176 Cat engine.
It has a couple issues that I need help with-
It has the 'door open' indicator lamp on the console illuminated. Which doors are signaling the light? All bay doors? Just eng doors? where are the switches on the doors?

And... I want to change the fuel filters. The bus is on a road trip today so I cant have a look in person. I pulled the service records from P/O and went to NAPPY to get the filters. The counter guy handed me 2 spin ons like my MC8 uses, But IIRC this C3 has a large white metal canister filter with a drain on the bottom, located beside the A/C compressor. I figured that this was the only filter and it would just be a paper element. Does it also have primary and secondary filters? Whats the procedure for service on the big bannister filter?

Thanks a lot, Chuck

[buswarrior]

At some point, not sure of the year or model, MCI started using magnetic proximity switches on all of the doors.

Circular, a little larger than a quarter.

With a partner, check for voltage at the sensors, check for physical clearance, a bent door edge will put it too far away, and, ultimately, start shorting the sensors. Try not to pierce wires, that will give you grief with corrosion down the road...

happy coaching!
buswarrior