Case IH 6 – ICU: Wheel Speed Sender Open Circuit

The control module has detected a break in the electrical circuit for the wheel speed sensor. The underlying condition is typically a disconnected plug, a severed wire in the harness, or an internal failure (open circuit) within the sensor itself, which prevents wheel speed data from being transmitted.

• MXM
• MXM series
• MX series Maxxum

1. 1

   Inspect the Instrument Control Unit (ICU) and the wheel speed sender on the axle/transmission for loose connections, unseated plugs, damaged wires, or signs of wear.

2. 2

   Ensure the tractor's battery is fully charged and connections are tight, as weak batteries can cause voltage fluctuations that trigger false ICU/EIC errors.

3. 3

   Disconnect the processor connector (ICU) and the wheel speed sender connector, then trace and test the wiring harness between the two points using a multimeter to check for an open circuit or a short to ground.

4. 4

   Test the sensor itself for an internal open circuit. If the wiring harness is good but the open circuit remains at the sensor terminals, the sensor is faulty.

1. 1

   Disconnect Power

   Disconnect the tractor's battery to protect the electronic control systems during repair.

2. 2

   Locate the Sensor

   Locate the wheel speed sender (typically mounted on the rear axle housing or transmission case).

3. 3

   Inspect and Clean

   Unplug the sensor. Clean the connector pins with electrical contact cleaner and check for pushed-back pins or corrosion.

4. 4

   Repair Wiring (If Applicable)

   If the diagnostic continuity test revealed a broken wire in the harness, splice and repair the wire using weather-sealed connectors, or replace the affected harness section.

5. 5

   Replace the Sensor (If Applicable)

   If the sensor failed the internal continuity test, unbolt the old sensor, install the new wheel speed sender, and torque to OEM specifications.

6. 6

   Reassemble and Clear Codes

   Reconnect the sensor plug and the battery. Use a tractor diagnostic tool to clear the error codes. If a tool is unavailable, the battery disconnect may have already reset the electronic control system. Test drive the tractor to ensure the speedometer works and the code does not return.