John Deere 191.03 – PTA (Power Train) / TCU (Transmission Control Unit): Sensor for Transmission Output Speed, Voltage at Channel 1 Too High

The Transmission Control Unit (TCU) has detected a voltage from the transmission output speed sensor that is above the normal operating range. This indicates an issue with the sensor itself or its associated electrical circuitry. The sensor monitors the rotational speed of the transmission's output shaft, which is crucial for proper gear shifting and overall transmission performance.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 6820
• 6920
• 6920S
• 5050E
• 5065E
• 5075E
• 5085E
• 5090E
• 310SK
• 315SK
• 6R Series
• 7R Series
• 8R Series
• 5000-series
• S690
• 250D
• 300D

1. 1

   Inspect the sensor circuit (lead 6081 for channel 1) between the transmission output speed sensor and the TCU/PTA for any signs of a short to power/battery.

2. 2

   Examine the connectors at the sensor and the module to ensure they are secure, clean, and free of corrosion or bent pins.

3. 3

   Use a multimeter to measure the voltage at the signal input of channel 1. If the voltage is pegged high and the wiring harness tests good, the sensor has failed internally.

4. 4

   Check for related codes (such as 000191.11 or 000191.02) which indicate a frequency discrepancy between the transmission output speed sensor and the wheel speed sensor.

1. 1

   Safety First

   Park the machine on a level surface, engage the parking brake, turn off the engine, and relieve any hydraulic pressure.

2. 2

   Locate the Sensor

   Locate the transmission output speed sensor on the transmission housing (labeled as sensor B63 or B14 depending on the model).

3. 3

   Disconnect the Harness

   Carefully unplug the electrical connector from the sensor.

4. 4

   Remove the Sensor

   Unbolt and remove the faulty transmission output speed sensor from the transmission housing. Have a catch pan ready, as a small amount of transmission fluid may leak.

5. 5

   Install the New Sensor

   Lubricate the O-ring on the new sensor with clean transmission fluid (e.g., Hy-Gard) and install it into the housing. Torque the retaining bolt to OEM specifications.

6. 6

   Reconnect and Clear

   Reconnect the wiring harness. Turn the key on and use a diagnostic tool to clear the 000191.03 fault code from the PTA/TCU.

7. 7

   Test Drive

   Operate the machine to verify that the transmission shifts correctly and no longer defaults to manual mode.