Case IH 517651-04 - DEC – DEC: PTO rear two speed shaft size speed sensor - Voltage Below Normal, or Shorted to Low Source

The control module is detecting that the electrical circuit for the PTO shaft size speed sensor has a voltage reading that is lower than the acceptable operating range, typically indicating a short to ground in the wiring harness or an internal short within the sensor itself.

• MAGNUM AFS Connect

1. 1

   Inspect the wiring harness leading from the DEC to the rear PTO speed sensor for chafing, pinched wires, or melted insulation that could cause a short to ground.

2. 2

   Disconnect the sensor and measure the supply voltage at the connector (typically 5V or 8V depending on the system) to ensure the ECU is sending the correct reference voltage.

3. 3

   Use a multimeter to check for continuity to ground on the signal wire. If there is continuity to ground while disconnected from the sensor and ECU, the harness is shorted.

4. 4

   If the wiring tests good, evaluate the PTO speed sensor itself, as the internal circuitry has likely shorted to ground.

1. 1

   Repair or replace wiring harness

   Repairing or replacing the damaged section of the wiring harness if a short to ground is found.

2. 2

   Replace PTO speed sensor

   Replacing the PTO speed sensor if it has failed internally.

3. 3

   Clear fault codes

   Clearing the inactive fault codes from the DEC after the repair is verified.