John Deere 191.04 – PTA / TCU: Sensor for Transmission Output Speed, Voltage at Channel 1 Too Low

The control unit detects that the voltage at the signal input from Channel 1 of the transmission output speed sensor (B63 or B14, lead 6081) has dropped below the acceptable threshold, typically indicating a short to ground. The transmission may default to manual mode, or the machine may experience limited to no transmission functionality as a protective measure.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 7R series
• 310K
• 310SK
• 315SK
• 670D/G
• 872D/G

1. 1

   Inspect the Sensor Circuit: Check the wiring harness (specifically Channel 1 / lead 6081) for any signs of chafing, bare wires, or shorting to ground.

2. 2

   Examine Connectors: Ensure the connections at the transmission output speed sensor and the PTA/TCU module are secure, clean, and free of moisture or corrosion.

3. 3

   Test the Sensor Voltage: Use a multimeter to measure the voltage at the signal input of Channel 1 of the transmission output speed sensor. If the voltage reads abnormally low (near zero) while the circuit is powered, the sensor has likely failed internally.

4. 4

   Verify Control Unit Functionality: Ensure the PTA module is correctly processing signals. If the wiring and sensor test fine, the module itself may require a software update or replacement.

1. 1

   Preparation

   Park the machine on a level surface, engage the parking brake, turn off the engine, and remove the key. Allow the transmission to cool.

2. 2

   Locate the Sensor

   Locate the transmission output speed sensor (B63 or B14) on the transmission housing. On many models, it is located at the lower rear of the transmission or near the transmission cooler lines.

3. 3

   Disconnect

   Tag and carefully disconnect the electrical harness connector from the sensor.

4. 4

   Removal

   Remove the retaining bolt(s) holding the sensor in place. Carefully pull the sensor out of the transmission housing. Note: Have a plug or clean rag ready to cap the opening to prevent transmission fluid loss or dirt ingress.

5. 5

   Installation

   Lubricate the O-ring on the new sensor with clean transmission fluid. Insert the new sensor into the housing and tighten the retaining bolt to the specified OEM torque.

6. 6

   Reconnect

   Reconnect the electrical harness, ensuring the locking tab clicks into place.

7. 7

   Clear and Test

   Turn the ignition on, use a diagnostic tool to clear the 000191.04 PTA/TCU fault code, and test drive the machine to ensure the transmission shifts properly and the code does not return.