John Deere 523961.07 – PTQ / EPC / ACU / TIA / TIQ / UIC: Issue With Signals From The Forward/Reverse Lever / Park Lock Engagement Fault

The control unit detects an active signal from the park lock switch while the reverse drive lever is not in the neutral position, the operator attempts to move the reverse drive lever while the range shift lever is engaged in park, the park lock fails to physically engage despite being commanded, or a ground/travel speed signal is detected while the park position is commanded and confirmed engaged.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 7720
• 7820
• 7920
• 5080R
• 5090R
• 5100R
• 5080RN
• 5090RN
• 5100RN

1. 1

   Ensure the operator is not inadvertently moving the reverse drive lever out of neutral while the park lock is engaged.

2. 2

   Restart the tractor, cycle the gear selector, and operate the vehicle slowly in forward gear to see if the code clears or returns.

3. 3

   Check the functionality of the park lock switch to ensure it accurately detects the park position of the range shift lever.

4. 4

   Ensure the reverse drive lever sensors are correctly aligned, calibrated, and accurately detecting the neutral position.

5. 5

   Check the ground/travel speed sensor for accurate readings, as false speed readings can trigger this code.

6. 6

   Inspect the wiring and connectors associated with the reverse drive lever, park lock switch, and travel speed systems for damage, loose connections, or corrosion.

1. 1

   Clear and Retest

   Clear the code using a diagnostic tool. Restart the engine, leave the range shift lever in Park, and verify the reverse drive lever is in Neutral. If the code does not return, it was likely an operator error.

2. 2

   Test Electrical Connections

   If the code is active, use a multimeter to test the voltage and continuity of the wiring harness between the reverse drive lever, the park lock switch, and the respective control module (PTQ/EPC/ACU). Repair or replace any damaged wiring.

3. 3

   Replace Faulty Switches/Sensors

   If the wiring is intact, test the Park Lock Switch and the Reverse Drive Lever Position Sensor. Replace whichever sensor is failing to report its position accurately.

4. 4

   Inspect Ground Speed Sensor

   If the code is triggered by a mismatch between park engagement and tractor movement, inspect the transmission ground speed sensor. Replace it if it is sending erratic speed signals while the tractor is stationary.

5. 5

   Mechanical Inspection

   If all electrical components pass inspection, check the physical park lock mechanism and actuator inside the transmission for mechanical faults, binding, or obstructions that prevent it from engaging or disengaging.

6. 6

   Final Calibration

   After replacing any sensors or switches, reset the system and test the reverse drive lever and park lock to ensure proper operation.