Case IH 27 – EDC (Electronic Draft Control) or EHR (Electronic Hitch Control): Lift Arm Position Sensing Control Voltage Low (Short Or Open Circuit)

The voltage signal returning from the 3-point hitch lift arm position sensor (potentiometer) is below the acceptable threshold. The system interprets this low voltage as either a severed wire (open circuit), a wire shorting to ground, or an internal failure of the potentiometer itself.

• MXM
• CX50
• CX60
• CX70
• CX80
• CX90
• CX100
• MX80C
• MX90C
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170
• 7110
• 7120
• 7130
• 7140
• 7150
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Puma
• Steiger

1. 1

   Inspect the wiring harness and connectors leading to the lift arm potentiometer at the rear of the tractor for chafed wires shorting to the chassis or disconnected plugs.

2. 2

   Verify that the sensor is receiving its 5-volt reference signal from the controller. If the 5V reference is missing, the issue is in the wiring harness or the controller, not the sensor.

3. 3

   Induce a code change to test the sensor: Turn the key ON (engine off) and disconnect the potentiometer (should register Code 27/1027). Turn key OFF, reconnect, and start engine. If Code 24 appears, the sensor is communicating; if Code 27 persists, the potentiometer or wiring is faulty.

1. 1

   Preparation

   Park the tractor on a level surface, lower the 3-point hitch completely (if possible) to relieve tension, turn off the engine, and disconnect the battery.

2. 2

   Removal

   Locate the lift arm position sensor on the rear hitch rockshaft. Disconnect the 3-pin electrical connector.

3. 3

   Disconnect Linkage

   Unbolt the sensor connecting rod/lever that links the potentiometer to the lift arm.

4. 4

   Remove Sensor

   Remove the mounting bolts holding the potentiometer to the chassis and remove the unit.

5. 5

   Installation

   Mount the new potentiometer and reattach the sensor linkage rod. Reconnect the 3-pin electrical connector.

6. 6

   EDC Calibration

   Turn the key switch to the 'ON' position, disconnect the potentiometer to induce Error Code 24, and then reconnect it. Start the engine and set the engine speed to 1500 RPM. Move the position control lever fully down, and then fully up to allow the EDC module to learn the new minimum and maximum voltage limits of the sensor.