John Deere 2875.04 – FLC (Flex Load Controller) or VCU (Vehicle Control Unit): 4-Way Flasher Switch (S31) Input Short to Ground

The controller has detected that the input voltage from the 4-way flasher (hazard) switch exceeds the sensor's high voltage specification or the circuit is shorted directly to ground.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 344K
• 524K
• 544K
• 624K
• 644J
• 724J
• 744K
• 824K
• 944K
• 310J
• 315SJ
• 410E
• 710G
• 655B
• 755B

1. 1

   Intermittent Check: Turn the key switch ON, clear DTCs, cycle key OFF then ON. If DTC returns, fault is active. If not, check switch wiring (e.g., L30 BRN wire) for intermittent opens/shorts and FLC/VCU connectors for loose pins.

2. 2

   Controller Check: Start the engine and disengage the park brake. If the park brake light turns off, check FLC J2/J3 connectors (e.g., X12 pins C3 and D3) for loose connections. If not, proceed to the Wiring Check.

3. 3

   Wiring Check: Turn the key switch OFF, disconnect the 4-Way Flasher Switch (S31), remove the FLC/VCU harness connector, and use a multimeter to test the harness wires between the switch and the controller for a short to ground.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the battery negative cable to prevent electrical hazards.

2. 2

   Access the Switch

   Remove the console or dash panel trim required to access the rear of the 4-Way Flasher Switch (S31).

3. 3

   Inspect the Harness

   Visually inspect the wiring harness leading to the switch. Look for chafed wires rubbing against the frame or console brackets that could cause a short to ground.

4. 4

   Test the Switch

   If the harness tests good (no shorts to ground), use a multimeter to test the S31 switch itself for an internal short.

5. 5

   Replace Components

   If the switch is internally shorted, replace it. If the harness is damaged, repair the shorted wire.

6. 6

   Reassembly & Clearing Codes

   Reconnect the switch and the battery. Turn the key switch ON, clear the codes using SERVICE ADVISOR™ or the display monitor, and test the hazard lights to verify the repair.