Case IH 3327 – Engine ECU: Timeout of CAN Message TCO1 (Tachograph)

The Engine Control Unit (ECU) has lost communication with the Tachograph module over the Controller Area Network (CAN) bus because it did not receive the expected TCO1 data message within the programmed time limit.

• Case IH Magnum 235 - 340 (Series 4)
• Steiger
• Puma
• Farmall

1. 1

   Verify if the tractor is actually equipped with a tachograph (configuration check)

2. 2

   Check the CAN bus wiring (yellow CAN bus) for open circuits, short circuits to ground, or short circuits to power between the Engine ECU and the Tachograph

3. 3

   Bench test the CAN bus terminators (engine and cab) to ensure the bus has the correct resistance

4. 4

   Verify that the Tachograph module itself is receiving proper operating voltage and has a clean ground connection

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to safely test the network.

2. 2

   Visual Inspection

   Locate the Tachograph module and the Engine ECU. Inspect the wiring harness connecting them for chafing, pinched wires, or corrosion at the connector pins.

3. 3

   Test CAN Resistance

   Using a multimeter, measure the resistance across the CAN High and CAN Low pins at the diagnostic port or module connector. It should read approximately 60 ohms.

4. 4

   Test Terminators

   If the resistance is incorrect (e.g., 120 ohms or open), locate the two CAN bus terminators (engine and cab). Supply 12 volts to terminal 1 to bench test them according to the OEM manual. Replace any faulty terminators.

5. 5

   Check Module Power

   Reconnect the battery and turn the ignition ON. Measure the power and ground pins at the Tachograph connector to ensure the module is turning on.

6. 6

   Repair/Replace

   Repair any broken CAN wires or replace the Tachograph module if it has power and ground but is failing to communicate on an otherwise healthy CAN bus.

7. 7

   Clear Codes

   Use a dealer diagnostic tool (like the CNH EST) to clear the fault codes. If the tractor does not have a tachograph, use the tool to reconfigure the Engine ECU to disable the TCO1 message expectation.