Normal circuit

1. Turn the ignition switch to ON (II).
2. The driver's MPCS unit transmits a door lock switch message.
3. The MICU, relay control module, gauge control module, and keyless access control unit receive the door lock switch message.
4. The communication circuit test is passed.

Since the door lock switch message was received by all the ECUs expecting to receive a message, the communication circuit between those units is OK. There are multiple messages sent and received by each ECU during this time to insure that the communication circuit is intact.