U1255 Loss of Class II Serial Data Fault

DTC U1255 Loss Of Class II Serial Data Fault:

DTC U1255 Loss Of Class II Serial Data Fault:

CIRCUIT DESCRIPTION
The Body Control Module (BCM) receives a vehicle security powertrain status message from the Powertrain Control Module (PCM) through the Class II serial data link when turning the ignition switch to the RUN position.

CONDITIONS FOR SETTING THE DTC
The BCM sets DTC U1255 when the BCM does not receive a vehicle security powertrain status message from the PCM within 1 minute of turning ignition switch to the RUN position

ACTION TAKEN WHEN THE DTC SETS
^ The BCM stores DTC U1255 in memory.
^ The BCM sends a message to the Instrument Panel Cluster (IPC) to turn on the SECURITY indicator lamp through the Class II serial data link.

CONDITIONS FOR CLEARING THE DTC
^ U1255 DTC status changes from current to history when the BCM receives the vehicle security powertrain status message from the PCM.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ The following conditions may cause an intermittent malfunction to occur:
- An intermittent open in circuit 1132 or 1037.
- Poor connections at the BCM, PCM, or Splice Pack SP205.
- The BCM is open internally.
^ The BCM may store DTC U255 if certain diagnostics are performed between the Powertrain Control Module (PCM) and the Data Link Connector (DLC).
^ DTC P1626 will set in the Powertrain Control Module (PCM), when the ignition switch is in the RUN position with the BCM disconnected. When BCM diagnostics and repairs are completed, refer to the Engine Controls for additional information on PCM related DTCs. Powertrain Management

TEST DESCRIPTION
Number below refer to the step number on the diagnostic table.
3. Determines whether the malfunction is intermittent or the BCM is faulty.