It's the crank sensor!
Join Date: Nov 2007
Location: Central Minnesota
Therein lies the danger of washing the engine..............
The crank sensor is a very common cause for the NO BUS, but theoretically, anything along the "bus" can give you this problem.
So other suspects would be any of the 5 volt engine management sensors AND the computer itself. And the power distribution center (black box); check that for water intrusion as well.
Try one by one, unplugging the sensors and then looking to see if the NO BUS message has gone away with that sensor unplugged. If you find the message is gone with any particular sensor out of circuit, you have found your culprit; replace that sensor.
If the above technique with the sensors doesn't find the problem, I think I'd consider getting a salvage yard computer.
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!