Case IH 517651-17 - DEC – DEC: Rear PTO Two-Speed Shaft Size Speed Sensor - Data valid but below normal operational range

The control module is receiving a valid signal from the rear PTO shaft size speed sensor, but the reading (frequency/voltage) is lower than the expected threshold for the selected PTO shaft size. This typically indicates a weak sensor signal, an excessive air gap between the sensor and the tone ring/gear, a failing sensor, or a poor electrical connection.

• MAGNUM AFS Connect
• Case IH Magnum 180
• Case IH Magnum 190
• Case IH Magnum 200
• Case IH Magnum 210
• Case IH Magnum 215
• Case IH Magnum 225
• Case IH Magnum 235
• Case IH Magnum 240
• Case IH Magnum 245
• Case IH Magnum 250
• Case IH Magnum 260
• Case IH Magnum 275
• Case IH Magnum 280
• Case IH Magnum 290
• Case IH Magnum 305
• Case IH Magnum 310
• Case IH Magnum 315
• Case IH Magnum 340
• Case IH Magnum 380
• Case IH Puma 115
• Case IH Puma 125
• Case IH Puma 140
• Case IH Puma 150
• Case IH Puma 155
• Case IH Puma 165
• Case IH Puma 185
• Case IH Puma 200
• Case IH Puma 215
• Case IH Puma 220
• Case IH Puma 230
• Case IH Puma 240
• Case IH Maxxum 100
• Case IH Maxxum 110
• Case IH Maxxum 115
• Case IH Maxxum 120
• Case IH Maxxum 125
• Case IH Maxxum 130
• Case IH Maxxum 140
• Case IH Maxxum 145
• Case IH Maxxum 150

1. 1

   Visual Inspection: Inspect the wiring harness leading to the PTO speed sensor on the rear PTO housing. Look for chafing, rodent damage, or melted wires.

2. 2

   Connector Check: Disconnect the sensor and inspect the pins. Look for corrosion, bent pins, or moisture ingress. Ensure the connector locks tightly when reconnected.

3. 3

   Sensor Mounting: Verify that the sensor is securely bolted to the PTO housing. A loose sensor will increase the air gap to the internal gear, causing a 'below normal range' weak signal.

4. 4

   Check for Related Codes: Look for accompanying hard-fault codes such as 5030 (Shaft size speed sensor open or short to Vbat) or 5031 (Shaft size speed sensor short to GND), which would point to a definitive wiring short rather than just a weak signal.

5. 5

   Tone Ring/Shaft Inspection: If the sensor is removed, use a borescope or flashlight to inspect the internal tone ring/gear for damage or excessive debris buildup that could disrupt the magnetic field.

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Sensor

   Locate the dual PTO speed sensor on the rear PTO housing assembly.

3. 3

   Clean the Area

   Thoroughly clean the area around the sensor with brake cleaner or compressed air to prevent dirt from falling into the PTO housing when the sensor is removed.

4. 4

   Disconnect

   Unplug the electrical connector from the sensor.

5. 5

   Removal

   Remove the retaining bolt holding the sensor in place. Carefully twist and pull the sensor out of the housing. Note: Have a catch pan ready, as a small amount of transmission/hydraulic fluid may seep out.

6. 6

   Preparation of New Sensor

   Lubricate the O-ring on the new sensor with clean hydraulic/transmission fluid to prevent tearing during installation.

7. 7

   Installation

   Push the new sensor fully into the housing until it seats flush. Install and tighten the retaining bolt to OEM torque specs (do not overtighten, as the sensor body is plastic).

8. 8

   Reconnect

   Plug the electrical harness back into the sensor.

9. 9

   Test

   Reconnect the battery, start the tractor, and engage the PTO. Verify that the DEC registers the correct shaft speed and that the 517651-17 code moves to an inactive/historic state. Clear the codes using the cab display or diagnostic tool.