Case IH 69 – Transmission Controller (Transmission ECU / TCU): Wheel Speed Sensor Low Error

The control module is receiving an abnormally low, erratic, or completely missing signal from the wheel speed sensor.

• JXC
• JX Series
• Farmall Series
• Maxxum
• Puma
• TN Series
• TNA Series
• TND Series
• TNS Series
• TN60A
• TN70A
• TN75A

1. 1

   Inspect the wheel speed sensor wiring harness for chafing, cuts, or melted insulation

2. 2

   Disconnect the wheel speed sensor connector and check for water intrusion, corrosion, or pushed-back pins

3. 3

   Ensure the sensor is securely mounted to the transmission housing/final drive to prevent an increased air gap

4. 4

   Use a multimeter to check for continuity between the sensor connector and the Transmission ECU harness, and verify the 5V or 12V reference voltage

5. 5

   Connect the CNH Electronic Service Tool (EST) to monitor the wheel speed sensor output live while moving the tractor

1. 1

   Safety First

   Park the tractor on a level surface, engage the parking brake, and turn off the engine. Disconnect the battery's negative terminal to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the wheel speed sensor, typically mounted on the side of the transmission housing or near the rear axle/final drive housing.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor.

4. 4

   Removal

   Remove the retaining bolt holding the sensor in place. Carefully twist and pull the sensor out of the housing. Note: Do not pry aggressively, as plastic sensors can break off inside the housing.

5. 5

   Clean

   Wipe the mounting port clean of any dirt, oil, or metallic debris.

6. 6

   Installation

   Lubricate the O-ring on the new sensor with a small amount of clean transmission oil. Insert the new sensor into the housing and tighten the retaining bolt to OEM torque specs.

7. 7

   Reconnect

   Plug the electrical connector back in, ensuring it clicks and locks securely.

8. 8

   Test

   Reconnect the battery. Start the tractor and perform a short test drive. The "Fixed Mod" status means the code may need to be cleared via the EST, or it will move to a stored/inactive state once a valid speed signal is registered.