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FAULT CODE 285

SAE J1939 Multiplexing PGN Timeout Error - Abnormal Update Rate

Overview

CODE	REASON	EFFECT
Fault Code: 285	SAE J1939 Multiplexing PGN Timeout Error - Abnormal Update Rate. The Cummins	One or more multiplexed devices will
PID:	engine control module (ECM) did not receive a multiplexed message from an OEM	not operate properly. One or more
SPN: 639	vehicle electronic control unit within the time limit or did not receive it at all.	symptoms will occur.
FMI: 9
LAMP: Amber
SRT:

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Circuit Description

Normally, switches, accelerators and other components are connected to the engine ECM directly through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic control 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 an OEM vehicle electronic control unit or transmission electronic control unit are received by the Cummins® engine ECM and used for controlling the engine. The Cummins® ECM and OEM vehicle electronic control unit(s) must be configured properly so that proper operation of the multiplexed components will occur.

Component Location

The engine ECM is located on the intake side of the engine. The SAE J1939 data link wiring and vehicle electronic control unit location varies by OEM.

Shop Talk

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 can possibly not actually be transmitting the message for that component. This can be caused when a multiplexed component is enabled in the Cummins® engine 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 bad SAE J1939 data link connection between the OEM vehicle electronic control unit and Cummins® ECM, a bad connection between the component and the OEM vehicle electronic control unit, bad OEM vehicle electronic control unit or bad Cummins® ECM. Contact the OEM for proper multiplexing configuration.

The INSITE™ electronic service tool can monitor multiplexed components. Refer to Troubleshooting Fault Code t05-285.