Another example of a shorted 429 Data Bus output wire.
In this case we had a "B" channel failure of the right engine EEC (FADEC on this aircraft).The EEC outputs go several places. The Standby Engine Indicator, the PIMU (Propulsion Interface and Monitor Unit), and EICAS.
We showed a bus failure on the PIMU and the right engine "B" display was blank on EICAS. (The image above was taken after the repair.)The Thrust Management Computer receives engine data from the PIMU. (On some aircraft, the TMC receives data from the EEC directly without the PIMU as a go-between.) We showed a failure for that also on the PIMU.
We found a shorted blue wire to shield on the twisted pair wires coming from the engine. This wire was before the terminal block that splits the signal to all the user components.