Circuit DescriptionNormally, switches, accelerators, and other components are connected to the engine electronic control module (ECM) directly through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic control unit (VECU) or transmission electronic control unit (ECU) in the cab. Then component values and states from components such as sensors, accelerators and switches can be transmitted from the OEM VECU to the Cummins? engine ECM over the SAE J1939 data link.

Messages sent from OEM VECUs or transmission ECUs are received by the Cummins? engine ECM and used for controlling the engine. The Cummins? ECM and OEM VECU(s) must be configured properly so that proper operation of the multiplexed components will occur.

Component LocationThe SAE J1939 data link wiring and the SAE J1939 devices vary by OEM options.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the key switch is in the ON position or when the engine is running.

Conditions for Setting the Fault CodesThe ECM did not receive a message from the multiplexed device.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkWhen this fault code is active, some multiplexed devices may not function as desired.

Possible causes of this fault code include:

When the ECM is set up properly (components enabled and OEM VECU source addressed correctly) to receive information from an OEM VECU, but the OEM VECU is actually transmitting a message that says that component is not available for multiplexing. This can be caused when a multiplexed component is enabled in the Cummins? ECM, but the OEM VECU source address of the VECU transmitting the component message is incorrect in the Cummins? ECM, or the OEM VECU is not set up to transmit the multiplexed component message.This fault can also be caused by a bad J1939 data link connection between the OEM VECU and Cummins? ECM, a bad connection between the component and the OEM VECU, a bad OEM VECU, or a bad Cummins? ECM. It may be necessary to contact the OEM for proper multiplexing configuration.It is possible to use INSITE? electronic service tool to monitor multiplexed components.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Cause:1) OEM harness2) ECM failure