Ok, I thought I’d post the solution as others may benefit. CAN B on a 2006 RAM is no ordinary canbus. Voltages (measured with voltmeter) are 0.5 and 4.5 volt. Very confusing to the normal approx. 2.5 volt values.
And there are no termination resistors uses in any computer or wiring harness.
My ‘no bus’ (and no crank-no start) problem was solved by replacing the instrument cluster. The previous owner put a 2007 cluster in this 2006 truck. It looks 100% identical, lights up and performs the self test, but it will not communicate.
Hope this helps others as well.
