Case IH 19275 – VCM (Vehicle Control Module): Timeout of CAN-Transmit-Frame Acknowledgment (ACK) occurred

A control module transmitted a data frame onto the network but did not receive the required acknowledgment (ACK) signal from the receiving modules within the programmed time limit. This typically points to an open circuit, a shorted CAN bus line, a failed terminating resistor, or an unresponsive module on the network.

• Tier 4b
• Case 580N
• Case 580SN
• Case 580SN WT
• Case 590SN

1. 1

   Connect the Case Electronic Service Tool (EST) and retrieve faults from all controllers to see if the ECU or TRX are also logging communication errors.

2. 2

   With the machine powered off and the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the diagnostic connector (should read approximately 60 ohms).

3. 3

   Inspect the CAN backbone wiring harness between the VCM, the Engine ECU, and the Transmission Controller for chafing, corrosion, or loose pins.

1. 1

   Disconnect negative battery terminal.

2. 2

   Isolate the CAN bus segments by unplugging the VCM, ECU, and TRX one at a time while monitoring the CAN line resistance to locate the short or open circuit.

3. 3

   Repair any damaged wiring in the CAN backbone.

4. 4

   If the wiring is intact and the terminating resistance is incorrect specifically when the VCM is plugged in, the VCM's internal resistor has failed, and the VCM must be replaced.

5. 5

   Reconnect all modules, clear the codes using the EST, and cycle the key to verify the CAN-Transmit-Frame Acknowledgment timeout does not return.