Case IH 2439 – CCU: Voltage from R3 switch too low

The control module monitors the circuit for the R3 switch (Transmission Range 3 switch or Hydraulic Remote 3 switch) and detects that the return voltage has dropped below the minimum acceptable threshold. This is most commonly caused by a short to ground in the wiring harness, a disconnected plug, or an internal failure of the switch itself.

• Farmall
• Case IH tractors
• Magnum
• Maxxum

1. 1

   Inspect the wiring harness running from the R3 switch to the CCU for chafing, pinched wires, or melted insulation that could cause a short to ground.

2. 2

   Disconnect the R3 switch and inspect the pins for corrosion, moisture, or pushed-back terminals. Do the same at the CCU connector.

3. 3

   With the key ON, check for the proper reference voltage at the switch connector.

4. 4

   Test the wiring harness for continuity between the switch connector and the corresponding CCU pin.

5. 5

   Test the circuit for a short to chassis ground.

6. 6

   Test the R3 switch itself for proper resistance/continuity when actuated. If it reads open or out of specification, the switch has failed.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery cable to prevent electrical spikes during repair.

2. 2

   Access the Switch

   Locate the R3 switch (refer to your specific model's schematic to confirm if it is located on the transmission housing or the hydraulic remote valve stack).

3. 3

   Repair Wiring

   If the diagnostic checks revealed a short to ground or broken wire, splice and heat-shrink the damaged section of the harness, or replace the harness section entirely.

4. 4

   Replace the Switch

   If the wiring is intact but the switch failed the continuity test, unthread/unbolt the defective R3 switch.

5. 5

   Install New Part

   Install the replacement R3 switch and securely reconnect the wiring harness plug.

6. 6

   Clear Codes

   Reconnect the battery. Turn the key to the ON position and use the tractor's enhanced keypad/display (or an electronic service tool) to access the stored error codes and clear code 2439.

7. 7

   Operational Test

   Operate the tractor and actuate the R3 function to ensure the voltage reads correctly and the fault code does not return.