Case IH 1027 – Electronic Draft Control (EDC) / Hitch Control Module: Lift arm position sensor - voltage too low

The control module is receiving a signal voltage from the rear rockshaft/lift arm position potentiometer that has dropped below the minimum acceptable threshold. This is typically caused by a short circuit to ground, an open circuit, or a completely failed internal potentiometer.

• Puma/Mid Range Magnum
• Maxxum
• Farmall
• MAXXUM T4E
• Puma series
• Steiger
• Magnum
• MX series (MX80C to MX170)
• CX series (CX50 to CX100)
• Farmall models

1. 1

   Inspect the mechanical linkage (sensor rod and lever) connecting the lift arm to the sensor to ensure it is not bent, broken, or disconnected.

2. 2

   Inspect the chassis harness connector at the sensor for moisture, corrosion, or backed-out pins (Note: Code 1031 is often related if the plug is loose).

3. 3

   Disconnect the sensor and turn the key ON, then use a multimeter to verify that the module is supplying a 5V reference and a good ground to the connector.

4. 4

   Check the signal wire from the sensor connector back to the EDC module to ensure it is not shorted to the chassis ground or broken.

5. 5

   Measure the resistance of the potentiometer while manually moving the lift arm linkage (Sensor Sweep Test). If the resistance drops out to zero or reads open, the sensor is internally faulty.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical spikes.

2. 2

   Disconnect Linkage

   Unbolt the sensor connecting rod/lever from the lift arm assembly.

3. 3

   Remove Sensor

   Unplug the electrical connector and remove the mounting bolts securing the lift arm potentiometer to the tractor chassis.

4. 4

   Install New Sensor

   Mount the replacement potentiometer and reattach the mechanical drive element/linkage.

5. 5

   Reconnect

   Plug the chassis harness back into the sensor and reconnect the battery.

6. 6

   Hitch Calibration

   Perform a hitch calibration procedure via the tractor's display or diagnostic service tool to teach the EDC module the new minimum and maximum voltage values for the fully lowered and fully raised lift arm positions.