Electronic Control System Signature, ISX and QSX15 Engines – FAULT CODE 285

J1939 Datalink Multiplexing


Fault Code: 285
PID: S231
SPN: 639
FMI: 9/9
LAMP: Yellow

The ECM expected information from a multiplexed device but did not receive it soon enough, or did not receive it at all.

At least one multiplexed device will not operate properly.

J1939 Datalink Multiplexing Circuit

Circuit Description

Inputs such as throttle pedals, switches, and sensors can be communicated to the ECM over the J1939 datalink. Messages sent from the vehicle electronic control units (VECU) are received by the ECM and used for controlling the engine. Both the ECM and VECU must be properly configured so that each device’s information is transmitted by the VECU and received by the ECM.

Component Location

The ECM is located on the intake side of the engine, near the front. The J1939 datalink wiring and VECU(s) vary by OEM options.

Shop Talk

This fault occurs when the ECM is set up to receive information about a multiplexed device from a VECU over the J1939 datalink and does not receive a message with that information. This fault can also be caused if the ECM does not get the information fast enough to control the engine properly. This condition can be caused by the J1939 datalink having an electrical problem, a lack of terminating plugs on the J1939 datalink backbone, the ECM not being set up to receive information, a multiplexed device that truly is not multiplexed, or a VECU not
being correctly set up to transmit information on one of its multiplexed devices.

Refer to Troubleshooting Fault Code t05-285.

Last Modified:  26-Oct-2010