WOMS
P code powertrain Medium severity

P1735 First Gear Switch Circuit Malfunction

The OBD2 code P1735 indicates a malfunction in the first gear switch circuit, which may affect the transmission's ability to properly detect when the vehicle is in first gear

Definition

The OBD2 code P1735 indicates a malfunction in the first gear switch circuit, which may affect the transmission's ability to properly detect when the vehicle is in first gear

Common causes

  • Faulty first gear switch
  • Wiring issues (shorts, opens, or corrosion)
  • Poor electrical connections
  • Malfunctioning transmission control module (TCM)
  • Faulty transmission range sensor
  • Software issues in the TCM
  • Mechanical issues within the transmission

Common misdiagnoses

  • Transmission control module (TCM) failure
  • Faulty transmission fluid temperature sensor
  • Wiring issues or shorts in the circuit
  • Faulty first gear switch
  • Incorrectly diagnosed transmission problems
  • Engine control module (ECM) issues
  • Problems with the vehicle speed sensor (VSS)
  • Misinterpretation of other transmission-related codes

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 Wiring and Connectors

    Visually inspect the wiring and connectors associated with the first gear switch. Look for signs of damage, corrosion, or loose connections. Repair or replace any damaged components

  3. 3. Test the First Gear Switch

    The first gear switch itself may be faulty. Use a multimeter to test the switch for continuity and proper operation. If the switch is defective, replace it

  4. 4. Check Transmission Fluid Level and Condition

    Low or contaminated transmission fluid can cause shifting issues. Check the fluid level and condition, and top off or replace the fluid as necessary

  5. 5. Inspect Transmission Control Module (TCM)

    The TCM may be malfunctioning or have a poor connection. Check for any updates or recalls related to the TCM and ensure that it is functioning properly

  6. 6. Examine the Transmission

    If the above steps do not resolve the issue, there may be internal transmission problems. Inspect the transmission for any signs of wear or damage

  7. 7. Clear Codes and Test Drive

    After performing repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns. Monitor the transmission's performance during the drive

  8. 8. Consult a Professional

    If you are unable to diagnose or fix the issue, it may be best to consult a professional mechanic or transmission specialist for further diagnosis and repair. By following these steps, you can systematically identify and address the cause of the P1735 code