Case IH 517651-03 - DEC – DEC: PTO rear two-speed shaft size speed sensor electrical circuit fault - voltage above normal

The PTO rear two-speed shaft size speed sensor signal voltage is above normal, indicating the circuit is either open or shorted to a high power source (Vbat / Battery Voltage).

• MAGNUM AFS Connect
• Magnum 180
• Magnum 190
• Magnum 200
• Magnum 210
• Magnum 220
• Magnum 225
• Magnum 235
• Magnum 240
• Magnum 250
• Magnum 260
• Magnum 280
• Magnum 290
• Magnum 310
• Magnum 340
• Magnum 380
• MX180
• MX200
• MX210
• MX220
• MX230
• MX240
• MX245
• MX255
• MX275
• MX285
• MX305

1. 1

   Visually inspect the wiring harness running from the DEC/CCH module to the rear PTO shaft size speed sensor for chafed wires, melted insulation, or pinch points.

2. 2

   Disconnect the sensor and inspect the connector pins for bent pins, pushed-back terminals, moisture, or corrosion that could bridge the voltage supply to the signal wire.

3. 3

   Using a multimeter, test the sensor's signal wire for continuity to ground and check for unwanted voltage (short to Vbat) while the sensor is unplugged.

4. 4

   If the wiring harness tests good, verify the internal circuitry of the PTO speed sensor, as it has likely failed and is shorting the reference voltage to the signal return.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent accidental shorts during repair.

2. 2

   Locate the Sensor

   Locate the rear PTO two-speed shaft size speed sensor at the rear PTO housing.

3. 3

   Disconnect and Remove

   Unplug the electrical connector from the sensor. Remove the retaining bolt(s) and carefully pull the sensor out of the housing.

4. 4

   Install New Sensor

   Lubricate the O-ring on the new sensor (if applicable) with clean transmission/hydraulic fluid. Insert the new sensor into the housing and tighten the retaining hardware to OEM torque specs.

5. 5

   Reconnect

   Plug the electrical harness back into the sensor, ensuring the locking tab clicks into place.

6. 6

   Clear Codes and Test

   Reconnect the battery, turn the key on, and use the Pro 700/1200 display or a diagnostic tool to clear the 517651-03 (or 5030) fault code. Start the tractor and engage the PTO to verify the code does not return and that the shaft speed registers correctly.