P1602

Circuit Description
A Class II 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.

Conditions for Running the DTC
^ The ignition is on.
^ System Voltage is greater than 8.2 volts.

Conditions for Setting the DTC
The PCM is detecting a loss of serial data from the EBCM for longer than 5 seconds.

Action Taken When the DTC Sets
^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
^ A history DTC is stored.

Conditions for Clearing the MIL/DTC
^ A history DTC will clear after 40 consecutive warm up cycles without a fault.
^ DTCs can be cleared by using a scan tool.

Diagnostic Aids
If no password is received a DTC P1610, P1626 and P1632 may be set.
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:
^ Backed out terminals or improper mating.
^ Broken locks.
^ Improperly formed or damaged terminals.
^ Poor terminal to wiring connections.
^ Physical damage to the wiring harness.
^ Corrosion.