Bus diagnosis: Notes

Fig 1: Identifying Bus Diagnosis

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Identifying Communicate Diagram Of Bus Diagnosis

Courtesy of SAAB-SCANIA OF AMERICA, INC.

In a bus system, all units must be capable of communicating with each other. For example, the engine cannot be started unless the Trionic system can receive the immobilization information sent out by the TWICE.

Bus faults can be caused by a bus lead breaking. This could result in one or more systems disappearing from the bus concerned (I or P), depending on where the break in the wiring harness occurred.

If a short circuit occurs in a bus lead, all systems will disappear from the bus concerned (I or P).

Note that if a short circuit occurs in the I-bus, then the DICE is the only bus system which can be contacted with the diagnostic tool.

In the event of a fault in grounding or power supply to one or more systems, these will cease to communicate.