Case IH 3420 – ENGINE Control Module (ECM / EDC): CAN Bus Received frames: DFC of Auxiliary Engine Shutdown Switch Message

An informational fault code indicating that the Engine Control Module (ECM) received a CAN bus message from another module requesting an external engine shutdown, typically because the Auxiliary Engine Shutdown Switch (Emergency Stop) was activated or there is a wiring issue simulating an active switch.

• Farmall
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR175
• SV series
• Compact Wheel Loaders
• 21F
• 121F
• 221F
• 321F Tier 4
• MX/TG series
• Compactors
• SV207E
• SV213E
• SV217E

1. 1

   Verify if the operator intentionally pressed the Emergency Stop / Auxiliary Shutdown switch

2. 2

   Scan the system for other active fault codes in the Vehicle Control Module (VCM) or Body Computer that may have triggered an engine protection shutdown

3. 3

   Physically inspect the Emergency Stop switch on the console/dash to ensure it is not mechanically stuck, damaged, or packed with debris

4. 4

   If the switch was not pressed, disconnect the switch and test for internal shorts

5. 5

   Inspect the wiring harness between the auxiliary shutdown switch and the control module for chafing, corrosion, or a short-to-ground

1. 1

   Reset the Switch

   If the E-Stop switch was manually depressed, twist or pull the button to reset it to its normal operating position.

2. 2

   Clear the Code

   Connect the Electronic Service Tool (EST). Clear the 3420 fault code and cycle the key. If the code does not return and the engine starts, no further repair is necessary.

3. 3

   Repair Wiring

   If diagnostic checks revealed a short or break in the harness between the switch and the VCM/ECM, repair the damaged wire and replace any corroded connector pins.

4. 4

   Replace the Switch

   If the switch is internally shorted or mechanically broken (fails to reset), remove the console panel, disconnect the electrical pigtail, unthread the retaining collar, and install a new Emergency Stop switch/contact plate.

5. 5

   Final Verification

   Turn the key to the ON position, verify the code is clear, and start the engine to confirm the repair.