U1016

DTC U1016

CIRCUIT DESCRIPTION
Each module connected to the class 2 serial data circuit monitors serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for state of health monitoring. Once an identification number is learned by a module, it will monitor for that modules node alive message. Each module on the class 2 serial data circuit is required to send a node alive message every 2 seconds. When a control module does not detect a node alive message from a learned identification number for 5 seconds, DTC U1001-U1254 will set.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC U1016 Lost Communications With Engine Control System (PCM)
- DTC U1040 Lost Communications With Electronic Brake Control Module (EBCM)
- DTC U1064 Lost Communications With Body Control Module (BCM)
- DTC U1088 Lost Communications With Restraints Control System (SDM)
- DTC U1096 Lost Communications With Instrument Panel Cluster (IPC)
- DTC U1128 Lost Communications With Radio

CONDITIONS FOR RUNNING THE DTC
- The power mode is RUN.
- The modules voltage supply is 9-16 volts.

CONDITIONS FOR SETTING THE DTC
A message from a learned control module has not been detected for the past 5 seconds.

CONDITIONS FOR CLEARING THE DTC
- A current DTC will clear when a node alive message from the failed identification number is detected on the class 2 serial data circuit or at the end of the current ignition cycle.
- A history DTC clears when the ignition is cycled 100 times without a repeat of the malfunction.

DIAGNOSTIC AIDS
- When more than one loss of communication DTC is set in either one module or in several modules, diagnose the DTCs in the following order:
- Current DTCs before history DTCs, unless instructed otherwise in the diagnostic table.
- The DTC which is reported the most times.
- From the lowest number DTC to the highest number DTC.
- When multiple loss of communication DTCs are set, the cause is likely to be two opens in the class 2 serial data circuit. Use the class 2 serial data circuit schematic in order to determine the location of the opens. Refer to Data Link Connector (DLC) Schematics.

TEST DESCRIPTION

Steps 1-8:

The number below refers to the step number on the diagnostic table.
6. The module which was not communicating on the class 2 serial data circuit may have set the Loss of Communication DTCs for the modules it was monitoring.