U0073

DTC U0073 Control Module Communication Bus Off

Circuit Description

The ECM the variable nozzle turbocharger (VNT) control module the glow plug control module (GPCM) the instrument panel (IP) cluster the data recording module (DRM) and the transmission control module (TCM) communicate control and diagnostic information via a controller area network (CAN) communication bus. The ECM monitors CAN operational status by expecting a constant flow of messages from each module. If the ECM sets CAN Bus OFF status this DTC will set.

Condition for Running the DTC

^ The battery voltage is between 8 to 16 volts.
^ The ignition switch is ON.
^ The engine is running.

Condition for Setting the DTC

^ The ECM detects the CAN Bus OFF status.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM limits fuel injection quantity.
^ The ECM inhibits EGR control.
^ The ECM inhibits DPF regeneration control.
^ The ECM inhibits cruise control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section.
^ Parallel resistance of the 1200 resistor in the ECM and the TCM (automatic transmission) or CAN resistor 1 (manual transmission) should be 600.

Notice: If the TCM has DTCs set, clear the DTCs in the TCM first.

Circuit/System Testing DTC U0073