CM850 Electronic Control System – FAULT CODE 286

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Overview

SAE J1939 Multiplexing Configuration SMALL | MEDIUM | LARGE

SAE J1939 Multiplexing Configuration SMALL | MEDIUM | LARGE

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 OEM Vehicle Electronic Control Unit (VECU) or Transmission ECU in the cab, or a System Intergration Module (SIM) in marine applications. Then component values and states from components such as sensors, accelerators and switches can be transmitted from the OEM VECU or SIM to the Cummins® engine ECM over the SAE J1939 data link.

Messages sent from OEM VECUs, Transmission ECUs. or SIM 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 Location

The engine ECM is located on the intake side of the engine. Refer to Procedure 100-002 in Section E.The J1939 data link wiring and VECU location varies by OEM. The SIM is located on the engine, or in the Vessel Interface Panel (VIP) in marine applications.

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 expects to receive a valid J1939 message from a multiplexed device for more than 1 second.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• The multiplexed device will not operate.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM. Refer to Procedure 019-032 in Section 19.

This fault can occur 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.

It is possible to use INSITE™ electronic service tool to monitor multiplexed components.

Refer to Troubleshooting Fault Code t05-286