Case IH 19388 – Engine Control Module (ECM): Timeout of CAN-Receive-Frame Torque / Speed control from ACC to ECM through TSC1_ACCR message active.

The Engine Control Module (ECM) has stopped receiving the expected Torque/Speed Control 1 (TSC1_ACCR) CAN messages from the ACC (Adaptive Cruise Control / Vehicle Speed Control system) within the required timeframe, which may result in limited engine performance or disabled cruise functions.

• Tier 4b
• Puma
• Magnum
• Optum
• Steiger
• T7
• T8
• T9

1. 1

   Verify battery and alternator voltage, as high or low system voltage can temporarily disable CAN power stages and trigger communication timeouts.

2. 2

   Using a multimeter, check the communication equipment's CAN-High (CAN-H) and CAN-Low (CAN-L) lines. Both should show a voltage to ground of approximately 2.5V when the system is active.

3. 3

   Visually inspect the CAN bus wiring harness between the ACC system/cab controllers and the ECM for chafing, pinch points, or melted insulation.

4. 4

   Disconnect the ECM and ACC connectors to check for pushed-back pins, bent terminals, moisture intrusion, or corrosion.

5. 5

   With the battery disconnected, measure the resistance across CAN-H and CAN-L. A healthy CAN bus should read approximately 60 ohms. A reading of 120 ohms indicates a missing or failed terminating resistor, while a reading near 0 ohms indicates a short circuit.

1. 1

   Power Down

   Turn off the ignition switch and disconnect the negative battery cable to prevent electrical spikes during testing.

2. 2

   Isolate the Fault

   Based on the diagnostic checks, locate the break or short in the CAN bus wiring between the cab control modules (ACC) and the engine ECM.

3. 3

   Repair Wiring

   If a damaged wire is found, repair the CAN-H or CAN-L wire using OEM-approved twisted-pair splicing techniques to prevent electromagnetic interference. If the damage is extensive, replace that section of the wiring harness.

4. 4

   Clean Connections

   If the wiring tests good but connectors are corroded, clean the ECM and ACC connector pins with electronic contact cleaner and apply dielectric grease before reconnecting.

5. 5

   Reboot and Clear

   Reconnect the battery. Turn the key to the ON position to reboot the modules. Connect the Case IH Electronic Service Tool (EST) to clear the inactive fault codes.

6. 6

   Module Verification

   If the wiring, voltages, and terminating resistors are all perfectly intact but the code immediately returns as 'Active,' the ACC module or the ECM itself may have a failed internal CAN transceiver, requiring a software reflash or hardware replacement by a Case IH dealer.