WOMS
P code powertrain Medium severity

P071C Transmission Mode Switch "A" Circuit High

The OBD2 code P071C indicates that there is a high voltage signal detected in the Transmission Mode Switch "A" circuit, which may suggest a malfunction in the switch or its wiring

Definition

The OBD2 code P071C indicates that there is a high voltage signal detected in the Transmission Mode Switch "A" circuit, which may suggest a malfunction in the switch or its wiring

Common causes

  • Faulty transmission mode switch
  • Wiring issues (shorts or open circuits)
  • Poor electrical connections
  • Faulty transmission control module (TCM)
  • Corroded connectors
  • Malfunctioning powertrain control module (PCM)
  • Software issues or updates needed
  • Low transmission fluid levels or quality

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Defective transmission range sensor
  • Wiring issues or shorts in the circuit
  • Faulty transmission fluid temperature sensor
  • Malfunctioning gear shift lever
  • Incorrectly installed or damaged transmission components
  • Software issues or outdated firmware in the TCM
  • Low transmission fluid levels or quality issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect the Transmission Mode Switch

    Visual Inspection: Check the transmission mode switch for any visible damage, corrosion, or loose connections

  3. 3. Wiring and Connectors

    Inspect the wiring harness and connectors for fraying, breaks, or poor connections. Ensure that all connectors are securely attached

  4. 4. Test the Transmission Mode Switch

    Multimeter Testing: 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. Functionality Check

    If possible, manually operate the switch to see if it responds correctly and if the readings change as expected

  6. 6. Check for Short Circuits

    Inspect the wiring for any signs of short circuits to ground or to other wires. A short can cause the circuit to read high

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

    Check the TCM for any signs of damage or corrosion. Ensure that it is properly connected and functioning

  8. 8. If the TCM is suspected to be faulty, it may need to be tested or replaced

  9. 9. Check for Ground Issues

    Ensure that the ground connections related to the transmission mode switch and TCM are clean and secure. Poor grounding can lead to erratic behavior

  10. 10. Clear Codes and Test Drive

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

  11. 11. Take the vehicle for a test drive to see if the code reappears. Monitor the transmission operation during the drive

  12. 12. 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 issues and OBD-II diagnostics.Additional Notes: - Always ensure that you are working safely and that the vehicle is properly supported if you are working underneath it. - If you are not comfortable performing these diagnostics, it is advisable to seek professional assistance. By following these steps, you should be able to identify the cause of the P071C code and take appropriate action to resolve the issue