Case IH 520329-09 - DEC – Drivetrain Electronic Controller (DEC): Rear PTO shaft speed sensor - valid data but above normal operating range (most severe level)

The Rear Power Take-Off (PTO) shaft speed sensor is successfully sending data to the controller, but the RPM reading is registering as abnormally high (above the normal operating range). This typically points to a failing sensor sending erratic/multiplied signals, a wiring short, or an improper sensor air-gap/mounting relative to the tone ring.

• MAGNUM AFS Connect
• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 225
• Magnum 305
• Magnum 315
• Magnum 400
• Maxxum 100
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Puma 115
• Puma 125
• Puma 140
• Puma 155
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 240
• Farmall 85C
• Farmall 95C
• Farmall 105C
• Farmall 115U
• Steiger AFS Connect

1. 1

   Inspect the Wiring Harness: Check the wiring harness and connector at the rear PTO speed sensor. Look for shorts to ground or open circuits. The standard wiring typically involves three pins: PTO Supply (often Green wire), PTO Speed Sensor Signal (often Orange wire), and Sensor Ground (often Black/White wire).

2. 2

   Check Sensor Mounting: Verify that the sensor is positioned correctly relative to the tone ring. A loose sensor can cause erratic, out-of-range readings.

3. 3

   Check for Contamination: Inspect the sensor connector for moisture, dirt, or dust ingress, which can skew electronic readings.

1. 1

   Locate the Sensor

   Access the rear PTO speed sensor, which is mounted on the rear transmission housing near the PTO output shaft (access can be tight depending on the tractor setup and rear hitch configuration).

2. 2

   Disconnect

   Unplug the 3-pin electrical connector from the sensor.

3. 3

   Remove

   Remove the retaining bolt holding the sensor in the housing and carefully pull the old sensor out.

4. 4

   Install

   Insert the new replacement sensor. Take your time positioning it correctly relative to the tone ring to ensure accurate readings. Secure it with the retaining bolt.

5. 5

   Reconnect

   Plug the electrical connector back in, ensuring the weather seal is intact.

6. 6

   Verify

   Start the tractor, engage the PTO, and check the cab display. Verify that the display shows steady RPM readings that match expected PTO speeds without triggering the over-range fault code.