Circuit Description
Normally, switches, accelerators, and other components are connected to the engine control module (ECM) through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic unit or transmission electronic control unit in the cab. Then, component values and states from components, such as sensors, accelerators, and switches, can be transmitted from the OEM vehicle electronic control unit to the Cummins® engine ECM over the SAE J1939 data link.
Messages sent from OEM vehicle electronic control units are received by the Cummins® engine ECM and used for controlling the engine. The Cummins® engine ECM and OEM vehicle electronic control unit(s) must be configured properly so proper operation of the multiplexed components will occur.
Component Location
The J1939 data link wiring and vehicle electronic control unit locations vary by OEM. See equipment manufacturer service information.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.
Conditions for Setting the Fault Codes
The ECM does not receive a valid J1939 message from the multiplexed aftertreatment 1 diesel exhaust fluid tank temperature sensor for more than 1 second.
Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
-This fault code can also be cleared with INSITE™ electronic service tool.
Shop Talk
When this fault code is active, some multiplexed devices may not function as desired.
This fault can occur for the following reasons:
-When the ECM is set up properly (components enabled and OEM vehicle electronic control unit source addressed correctly) to receive information from an OEM vehicle electronic control unit, but the OEM vehicle electronic control unit 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 vehicle electronic control unit source address of the vehicle electronic control unit transmitting the component message is incorrect in the Cummins® ECM or the OEM vehicle electronic control unit is not set up to transmit the multiplexed component message.
-This fault can also be caused by a malfunctioning J1939 data link connection between the OEM vehicle electronic control unit and Cummins® ECM, a malfunctioning connection between the component and the OEM vehicle electronic control unit, or a bad OEM vehicle electronic control unit or malfunctioning Cummins® ECM. It can be necessary to contact the OEM for proper multiplexing configuration.
-It is possible to use INSITE™ electronic service tool to monitor multiplexed components.
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