WOMS
P code powertrain Medium severity

P071D Transmission Mode Switch "B" Circuit

The OBD2 code P071D indicates a malfunction in the Transmission Mode Switch "B" Circuit, which is responsible for signaling the transmission control module about the selected transmission mode

Definition

The OBD2 code P071D indicates a malfunction in the Transmission Mode Switch "B" Circuit, which is responsible for signaling the transmission control module about the selected transmission mode

Common causes

  • Faulty transmission mode switch
  • Wiring issues (shorts, opens, or corrosion)
  • Poor electrical connections
  • Faulty transmission control module (TCM)
  • Software issues in the TCM
  • Malfunctioning gear selector assembly
  • Low transmission fluid levels or contamination
  • Internal transmission problems

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Defective transmission range sensor
  • Wiring issues or shorts in the circuit
  • Malfunctioning transmission solenoids
  • Incorrectly diagnosed engine control module (ECM) issues
  • Problems with the vehicle speed sensor (VSS)
  • Low transmission fluid levels or quality issues
  • Faulty or misaligned gear shift linkage

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues

  2. 2. Inspect the Transmission Mode Switch

    Locate the transmission mode switch and visually inspect it for any signs of damage, corrosion, or loose connections

  3. 3. Ensure that the switch is properly mounted and not misaligned

  4. 4. Test the Switch

    Use a multimeter to test the resistance and continuity of the transmission mode switch. Compare the readings to the specifications in the vehicle’s service manual

  5. 5. Check for proper operation of the switch in all modes (e.g., park, reverse, drive)

  6. 6. Check Wiring and Connectors

    Inspect the wiring harness and connectors associated with the transmission mode switch for any signs of wear, fraying, or damage

  7. 7. Ensure that all connectors are securely attached and free of corrosion

  8. 8. Inspect the Transmission Control Module (TCM)

    Check the TCM for any signs of damage or corrosion. If the TCM is faulty, it may not interpret the signals from the transmission mode switch correctly

  9. 9. If possible, perform a software update or reset the TCM to see if that resolves the issue

  10. 10. Check for Ground Issues

    Ensure that the ground connections related to the transmission mode switch and TCM are secure and free of corrosion

  11. 11. Perform a Visual Inspection of the Transmission

    Inspect the transmission for any external leaks or damage that could affect the operation of the transmission mode switch

  12. 12. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner

  13. 13. Take the vehicle for a test drive to see if the code reappears

  14. 14. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission systems. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P071D code