A few quesrions

The answers in order, yes, yes and maybe. The washer bottle is non serviceable. You can in plug the sensor for the seat belt and stick a paper clip in the 2 terminals. And the software updates are usually for aftertreatment issues or certain minor glitches. Not required but will definitely help with pesky MIL lights etc

 

Why do you need a light for washer fluid? Check it every pretrip and fuel stop. I would cut the wire on the seat belt and leave the motor alone if it ain't broke

 

Well first off if the sensor (float) is stuck it will throw an "i" light to inform the driver that the level is low. Gotta love all the sensors, also gotta admit not all drivers have good common sense so a dummy light is needed. As for cutting the harness for the seat belt, that accomplishes nothing, just shows an open circuit and will still chime. Need to bypass it. And ecm updates although not required with throw an ecm maintenance message on the driver display.

 

Then it's the wrong truck

 

on my volvo the windshield fluid tank is behind the batteries and difficult to see which why they have the sensor in the 1st place but i usually top mine off every few days so it doesnt get low anyway

 

My last freightliner had seat belt " bing, bing, bing " all the time. The contacts where the belt clips into the belt receiver wear out. Yes you can by pass it. Unplug it where it comes through the floor and attaches to the seat. Just fold a piece of wire in a U and plug it into the holes, that bridges the circuit. DON'T let bear catch you.