Case IH 1762-03 - UCM – UCM: Charge pump pressure sensor voltage high

The control module is receiving a signal voltage from the hydraulic charge pump pressure sensor that exceeds the normal operating range (typically above 4.5V or 4.75V on a 5V reference circuit). This usually indicates an open ground wire, a signal wire shorted to a power source, or an internal failure of the sensor itself.

• MAGNUM AFS Connect
• Steiger AFS Connect

1. 1

   Locate the charge pump pressure sensor on the transmission/hydraulic charge pump housing and visually inspect the sensor connector and wiring harness for rubbed-through insulation, corrosion, or pushed-out pins.

2. 2

   Disconnect the sensor, turn the key to the ON position (engine off), and use a multimeter to verify the sensor is receiving the correct reference voltage (typically 5V) and has a solid path to ground. An open ground circuit will cause the signal voltage to float high.

3. 3

   Check the signal wire for a short to power (12V or 5V) between the sensor connector and the UCM harness.

4. 4

   If the reference voltage and ground are good, and the signal wire is not shorted to power, the sensor has likely failed internally and requires replacement.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, and engage the parking brake. Relieve any residual hydraulic pressure in the system.

2. 2

   Locate the Sensor

   Locate the charge pump pressure sensor on the primary hydraulic power system / transmission charge pump housing.

3. 3

   Removal

   Disconnect the electrical connector from the sensor. Place a catch pan or rag underneath to catch any residual hydraulic fluid. Use a wrench to unthread the faulty sensor from the pump housing.

4. 4

   Installation

   Thread the new charge pump pressure sensor into the housing. Tighten to the OEM torque specification (do not overtighten, as this can damage the O-ring or threads).

5. 5

   Reconnection

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

6. 6

   Validation

   Start the tractor and observe the monitor. Verify that the 1762-03 fault code changes from "Active" to "Inactive". Clear the inactive code using the Pro 1200 monitor or the Case IH Electronic Service Tool (EST). Check the sensor fitting for any hydraulic leaks.