Case IH 520242-02 - PCM – PCM: CAN-3 Data Erratic, Intermittent Or Incorrect

Communication failure, timeout, or loss of messaging on the CAN-3 network. The system is receiving corrupted, unstable, or no data across this specific CAN network.

• MAGNUM AFS Connect
• Magnum series tractors
• Steiger series tractors
• Optum series tractors
• Puma series tractors
• Axial-Flow 260 combines
• Austoft 9900 cane harvesters
• 50 Series Patriot sprayers
• Legacy machines equipped with Case IH Pro 1200 Guidance Kit or AFS Pro 700 displays

1. 1

   Check Modem LED Status: Locate the PCM/modem and verify that the green power LED is steady ON (if blinking, a firmware update is in progress and should not be interrupted)

2. 2

   Cycle Power: If the LED is steady ON but the fault is active, cycle the power to the system to see if the modem re-establishes communication

3. 3

   Inspect Diagnostic Connectors: Verify the green CAN-3 connector is secure and properly pinned on pins C and D of the factory diagnostic connector

4. 4

   Check CAN Terminators: Verify that the CAN-3 terminators are intact and properly seated (typically located in the cab roof and at the end of the line)

1. 1

   Power Cycle & Firmware Check

   Turn the machine on and observe the PCM. If the green LED is blinking, wait for the update to complete. If it is solid, reboot the system.

2. 2

   Harness Inspection

   Trace the CAN-3 wiring harness from the PCM to the diagnostic port and out to the implement/terminator. Look for chafing, pinched wires, or corrosion at the connectors.

3. 3

   Pin Testing

   Disconnect the CAN-3 harness and use a multimeter to check for continuity, shorts to ground, or shorts to power on the CAN-High and CAN-Low lines.

4. 4

   Terminator Resistance Test

   Measure the resistance across the CAN-3 network. A healthy CAN bus with two 120-ohm terminators should read approximately 60 ohms. If it reads 120 ohms, one terminator is missing or faulty. If it reads 0 ohms, there is a short circuit.

5. 5

   Repair/Replace

   Repair any damaged wiring or replace faulty CAN terminators.

6. 6

   Module Replacement

   If the wiring harness, pins, and terminators all test good, the PCM itself has likely suffered an internal failure and will need to be replaced and reprogrammed by a Case IH dealer.