Eaton Fuller Hybrid Transmission Fault Code 87 – CAN ECA Message (HCM)

Fault code for Eaton Hybrid Drive Systems models (MY08) EH-8E306A-U, EH-8E306A-UPG, EH-8E306A-UP, EH-8E306A-CD, EH-8E306A-T and EH-6E606B-CD. Read below to learn how to test, clear and fix fault code errors for your Freightliner, Mack, Peterbilt, Kenworth, Volvo, International, and heavy-duty truck and equipment. Controller Area Network (CAN) is a high-speed twisted pair 500K proprietary data link with one 120 ohm resistor at each end of the link. The Hybrid Control Module (HCM) is connected to the CAN data link at the 38-Way Connector. This link is used to transmit information to the HCM as well  as communicate or receive data from the other modules on the network like the Electric Clutch Actuator (ECA

Fault Code 87 – CAN ECA Message (HCM) Detection

The following preconditions must be met before the system detects the fault:

  • HCM ignition voltage is greater than 7 volts and less than 16 volts.
  • HCM CAN Communication Link Fault is Inactive.

Note: When troubleshooting an Inactive code refer to the Product Diagnostic Mode (PDM)

Conditions to Set Fault Code Active

  • FMI 9 is set when the HCM fails to receive ECA data (like clutch position) for 30 consecutive messages or greater, and it is still communicating with other modules on CAN.

Fallback When Fault Code 87 is set the following conditions occur:

  • Red “Stop Hybrid” light illuminates.
  • Fault is stored in HCM memory.
  • Operation mode changes to “AutoShift Only” mode.
  • If the fault sets at power up, the engine will not crank.
  • Electric Motor/Generator Assist and Regeneration are disabled; however, the high-voltage relays remain powered.
  • If the fault occurs while driving, the ECA either maintains current clutch position or moves to the last position commanded by the HCM.

Conditions to Set Fault Code Inactive

Only Inactive faults can be cleared from the Transmission Electronic Control Unit (TECU) or HCM history using ServiceRanger. The TECU automatically clears the faults from history after 200 hours and the HCM automatically clears the faults from history after the fault has been Inactive for 200 hours.

This fault code can be caused by any of the following:

  • FMI 9
    • CAN Data Link
    • ECA

Fault Code 87 – CAN ECA Message (HCM) Test

Component Identification MY08 Systems:

HCM - Hybrid System Interface Connector

Harness Front View
(HCM – Hybrid System Interface Connector)

ECA 8 way connector Eaton Fuller transmission

ECA 8 way connector

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY08 Systems

Eaton Fuller HCM ECA Connection location in Eaton Fuller transmission

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