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A fault on the vehicle's data network rather than in any module attached to it. The distinguishing evidence is plural: several modules reporting lost communication with several others, in a pattern that does not centre on any one of them.

A bus is a shared pair of wires with a termination at each end, and it fails as a shared resource. One shorted conductor, one crushed section, or one module holding the line takes down communication for everything past that point — and every module reports its own view of the silence. Reading the pattern of who cannot hear whom localises the break better than any single code.

Two measurements settle most of it. Resistance across the pair with the ignition off should read about sixty ohms, since the two terminating resistors are in parallel — roughly a hundred and twenty means one termination or a section is missing. And disconnecting modules one at a time finds the one dragging the bus down, since a failed transceiver can hold the line and silence the whole network while looking healthy. Look where the loom crosses a hinge or a body seam, which is where the mechanical damage usually is.