Case IH 520330-09 - DEC – DEC (Drivetrain Electronic Controller): CAN VB2 abnormal update rate

The Drivetrain Electronic Controller (DEC) is not receiving expected CAN messages on Vehicle Bus 2 (CAN VB2) at the expected rate. This is a communication timeout error indicating that the DEC has lost communication with another module on that specific CAN bus, or the bus itself is experiencing an issue (such as an open circuit, short, or high traffic) preventing messages from getting through.

• MAGNUM AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Verify battery voltage and ground connections to the DEC and other modules on CAN VB2. Low voltage can cause modules to drop off the network.

2. 2

   Visually inspect the CAN VB2 wiring harness for physical damage, chafing, or loose connections along the transmission and chassis.

3. 3

   With the key off and battery disconnected, measure the terminating resistance of CAN VB2. It should read approximately 60 ohms. If 120 ohms: One terminating resistor is missing, or there is an open circuit in the bus. If 0 ohms: There is a short circuit between CAN High and CAN Low.

4. 4

   Check for other active CAN communication fault codes that might pinpoint a specific module that has gone offline and is causing the timeout.

5. 5

   Inspect the connectors at the DEC and other modules on the bus for corrosion, pushed-out pins, or moisture.

1. 1

   Power Down

   Turn off the key and disconnect the battery to prevent electrical spikes during testing.

2. 2

   Locate Components

   Locate the DEC (typically mounted near the transmission/drivetrain) and the CAN VB2 diagnostic port or splice block.

3. 3

   Test the Bus

   Using a multimeter, probe the CAN High and CAN Low pins on Vehicle Bus 2 to verify the 60-ohm resistance.

4. 4

   Trace the Harness

   If the resistance is out of spec, trace the wiring harness routing to locate the open or short circuit. Pay special attention to pinch points or rub marks near moving drivetrain components.

5. 5

   Clean and Reseat

   Disconnect the DEC connectors and inspect for water ingress or pin damage. Clean with electrical contact cleaner and apply dielectric grease if necessary. Reconnect securely.

6. 6

   Clear Codes

   Reconnect the battery, turn the key on, and use the Case IH Electronic Service Tool (EST) to clear the fault code.

7. 7

   Test Drive

   Operate the tractor to verify if the code returns. If the code returns and the wiring/terminating resistors are perfectly intact, the DEC or another module on the bus may require a software flash/update or physical replacement.