Case IH 19279 – Engine Control Module (ECM) or Aftertreatment Control Module (ACM): Timeout Error of CAN-Transmit-Frame AT1S

The AT1S (Aftertreatment 1 Service) CAN bus message broadcasting DPF soot and ash load percentage was not received within the expected timeframe, indicating an electrical communication failure.

• Tier 4b
• Steiger
• Magnum
• Puma
• Maxxum
• Optum
• Farmall

1. 1

   Inspect the CAN bus wiring harness (CAN High and CAN Low) between the ECM, ACM, and the DPF sensors for chafing, breaks, or heat damage from the exhaust.

2. 2

   Disconnect the DPF sensors and the ACM to inspect electrical connectors for corrosion, moisture intrusion, or pushed-out pins.

3. 3

   Verify that the DPF sensors and the Aftertreatment Control Module are receiving proper operating voltage and have a solid ground connection.

4. 4

   Perform a CAN bus resistance test with the battery disconnected by measuring resistance across the CAN High and CAN Low pins (should read approximately 60 ohms).

5. 5

   Check for other active CAN communication fault codes (e.g., AT1IG2 or A1DOC timeouts) that might indicate a broader network failure or bus overload.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent electrical spikes during repair.

2. 2

   Repair Wiring

   Repair or replace any damaged wiring or corroded connector pins found during the diagnostic checks.

3. 3

   Replace Faulty Sensor

   If the wiring, power, and ground are all verified as good, the communication loss is likely due to an internal failure of the DPF Delta Pressure Sensor or the Soot/PM Sensor. Remove the faulty sensor from the DPF housing and install the replacement.

4. 4

   Restore Power

   Reconnect the battery.

5. 5

   Clear Codes

   Connect the CNH Electronic Service Tool (EST) to clear the inactive fault codes.

6. 6

   Verify Communication

   Turn the key to the ON position and monitor the AT1S parameters (DPF Soot Load and Ash Load percentages) on the diagnostic tool to confirm the CAN message is now broadcasting successfully.

7. 7

   Regeneration

   Start the engine and perform a stationary/service DPF regeneration to ensure the aftertreatment system is functioning properly and the soot/ash load sensors are reading accurately.