It was not just a simple old school “resistance” type sensor, that would have been better of course. These sensors had a chip with firmware, an engineer’s “better idea”. They work like a radio signal transceiver on a modified sine wave sending signals back and forth to the ECM using the power voltage as only a “carrier” just like a radio. Without the ECM, cab computer, and the sensor “handshaking” and “seeing” each other the ECM and cab computer software would both agree to go into self protection mode and shut the engine down.
There was absolutely no need for this as a default in that application. If the level was fine, the driver could have ignored the red light on the dash and got it back to the shop to be repaired AFTER the load was delivered. The previous years did indeed allow this advantageous ability to still USE the truck when this particular unimportant non-critical sensor went bad. Alerting a driver and completely disabling are worlds apart in logic and rationality.
They are making everything far far more complicated than it should ever or need to be. We do not need rocket scientists or software engineers designing trucks. Ever... :)
Wow! Why so complicated? Just, as you say, overkill. We have a canbus and we are going to use it!