John Deere 177.03 – Transmission Control Module (PTA, EPC, PTP, CCU, or BIF): Transmission Oil Temperature Sensor Voltage Too High

The control unit has detected that the voltage at the signal input of the transmission oil temperature sensor is excessively high. The system interprets this high voltage as a temperature value below 34°C (29°F), which typically indicates that the sensor's circuit is either completely open (disconnected/broken wire) or shorted to a positive power lead.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5000 series (5G, 5M, 5E)
• 6000 series (6120-6520, 6130-6930, 6090MC-6110RC)
• 7000 series
• 8000 series
• 9230
• 9330
• 9430
• 9530
• 9630
• 450J
• 550J
• 650J
• 750J
• 850J
• 310G
• 310J
• 310K
• 325J
• 325K
• 410G
• 410J
• 410K
• 710G
• 710J
• 710K
• 540G-III
• 548G-III
• 640H
• 648H

1. 1

   Inspect Sensor Wiring: Visually inspect the wiring harness (specifically lead 6002, if applicable to your model) going to the transmission oil temperature sensor. Look for severed wires, chafing, or areas where the wire might be shorting to a positive battery/supply voltage.

2. 2

   Verify Connections: Disconnect the sensor and check the connector terminals for water intrusion, pushed-back pins, or corrosion. Ensure the connection is tight.

3. 3

   Check for Voltage Anomalies: With the key on, measure the voltage at the signal input wire at the sensor harness to confirm it is within the normal 5V reference operating range and not shorted to a 12V power source.

4. 4

   Test Sensor Functionality (Resistance Test): Remove the sensor from the circuit and measure its resistance with a multimeter. A healthy sensor should read approximately 1194 Ohms at 45°C (113°F), 979 Ohms at 50°C (122°F), and 808 Ohms at 55°C (131°F). An open circuit (infinite resistance) means the sensor has failed internally.

1. 1

   Locate the Sensor

   The sensor is typically threaded into the side or bottom of the transmission housing (e.g., on a 310J backhoe, it is located on the front right side of the transmission near the bottom).

2. 2

   Repair Wiring

   If the diagnostic checks revealed a broken wire or a short to power in the harness, splice and seal the damaged wire, or replace the affected harness section.

3. 3

   Replace the Sensor

   If the sensor is faulty, place a drain pan under the sensor location. Unplug the electrical connector, unthread the old B60/B6 temperature sensor from the transmission housing, install the new sensor (ensure the O-ring is in place if required), and tighten to OEM torque specifications. Reconnect the electrical harness.

4. 4

   Clear and Test

   Top off any lost transmission/hydraulic fluid. Turn the key on, clear the stored 000177.03 fault code via the monitor or service tool, and operate the machine to verify the transmission temperature reads accurately and the code does not return.