Case IH 6584-03 - DEC – Electronic Transmission Controller (ETC) or Transmission Control Unit (TCU): Transmission Hydrostatic Loop 2 Pressure - Voltage above normal, or shorted to high source

The controller is receiving a voltage signal from the hydrostatic loop 2 pressure sensor that exceeds the normal operating range. This condition is typically caused by the sensor's signal wire shorting to a high-voltage power source, an open ground circuit causing the voltage to float high, or an internal failure of the sensor itself.

• MAGNUM AFS Connect
• Puma CVT/CVX Series: 130, 145, 150, 160, 165, 170, 180, 185, 195, 200, 210, 215, 220, 230, 240
• Magnum CVT Series: 180, 190, 200, 210, 220, 225, 240, 250, 280, 310, 340, 380
• Optum Series: 270, 300
• Maxxum Series: 110, 115, 125, 130, 140, 150

1. 1

   Visual Inspection: Inspect the wiring harness leading to the Transmission Hydrostatic Loop 2 Pressure sensor for chafing, melted insulation, or pinch points that could cause the signal wire to short to a power wire.

2. 2

   Connector Check: Disconnect the sensor and inspect the pins for corrosion, moisture, or damage.

3. 3

   Circuit Testing: Use a multimeter to check the sensor's signal circuit for a "short to high source" (e.g., continuity between the signal wire and the 5V/12V supply wire).

4. 4

   Ground Verification: Check the sensor ground circuit. An open ground will often cause a sensor's signal voltage to peg at the maximum reference voltage, triggering an FMI 03 code.

5. 5

   Live Data Monitoring: If available, use the CNH Electronic Service Tool (EST) to monitor the live voltage of the Hydrostatic Loop 2 Pressure sensor. If the voltage remains pegged high when the sensor is unplugged, the fault is in the wiring harness or the controller. If the voltage drops when unplugged, the sensor is internally shorted.

1. 1

   Power down the machine and turn off the battery master disconnect switch to protect the transmission controller.

2. 2

   Locate the Transmission Hydrostatic Loop 2 Pressure sensor on the transmission valve block or hydrostatic pump assembly.

3. 3

   Disconnect the electrical harness from the sensor.

4. 4

   If diagnostic tests (above) proved the wiring harness is shorted, locate the damaged section of the harness, repair the wires, and seal with heat-shrink tubing.

5. 5

   If the wiring is intact and the sensor is internally shorted, use a wrench to carefully unthread the faulty pressure sensor from the transmission port. Have a rag ready to catch any residual hydraulic fluid.

6. 6

   Install the new OEM pressure sensor into the port and tighten to the manufacturer's specified torque.

7. 7

   Reconnect the electrical harness, ensuring the locking tab clicks into place.

8. 8

   Turn on the battery disconnect, key on the machine, and use the CNH EST diagnostic tool to clear the 6584-03 fault code.

9. 9

   Start the tractor and verify that the transmission engages properly and the code does not return.