U1064 MSM Loss of Serial Communications (PZM)

DTC MSM U1064-Loss Of Serial Communications (PZM):

CIRCUIT DESCRIPTION
While the ignition switch is in RUN, modules communicating on the Class 2 data bus send a "State of Health" (SOH) message every 5 seconds to ensure that the system is operating properly.

CONDITIONS FOR SETTING THE DTC
^ This DTC will set relay if DTC MSM Bl982, DTC MSM B1983, or MM DTC U1300 is not current.
^ The MSM does not receive an SOH message from the PZM after three consecutive monitoring cycles.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The MSM detects an SOH from the PZM.
^ The conditions for setting the DTC are no longer met.
^ The DTC will clear on every Power Mode Initialization.

DIAGNOSTIC AIDS
^ This serial data DTC does not normally represent a failure within the MSM. This is not true when there is an intermittent connection of the Class 2 data line(s) to the MSM. When serial data codes are history, know all possible serial data DTCs and which ones are set in each module, before diagnosing the Class 2 concern.
^ Clear all DTCs and cycle ignition to see if DTC was set erroneously.
^ If there are multiple DTCs, check for an intermittent short to ground in CKT 1807 PPL).
^ If DTC is current, attempt to establish communications with the PZM using the scan tool.
- If communications cannot be established with the PZM, refer to Body Control Module (PZM). Body Control Module
- If communications can be established with the PZM, then replace the MSM.
^ If the DTC is history, check for intermittent open in CKT 1807 (PPL).