The PCM uses the serial data circuit to communicate with various other devices and systems in the vehicle. The PCM ensures that communication remains established by monitoring the serial data circuit for state of health messages from the other devices using the circuit. If the PCM detects a loss of state of health serial data message from the EBCM/EBTCM, DTC P1602 will be set.A Class Il serial data communications system is used on this vehicle to allow various modules to communicate and share information with each other. This allows vehicle wiring to be reduced and the transmission and reception of multiple signals over a single wire. The messages carried on a Class II serial data streams are also prioritized. If two messages attempt to establish communications on the data line at the same time, the message with the higher priority will continue. The message with the lower priority message will wait. If a module cannot respond to the PCM, a DTC is stored.

The PCM is detecting a loss of serial data from the EBCM/EBTCM for longer than 5 seconds.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Any circuitry, that is suspected as causing an intermittent complaint, should be thoroughly checked for the following items: