WOMS
P code powertrain Medium severity

P0790 Normal/Performance Switch Circuit Malfunction

The OBD2 code P0790 indicates a malfunction in the normal/performance switch circuit, which typically affects the transmission's ability to switch between normal and performance driving modes

Definition

The OBD2 code P0790 indicates a malfunction in the normal/performance switch circuit, which typically affects the transmission's ability to switch between normal and performance driving modes

Common causes

  • Faulty normal/performance switch
  • Wiring issues (shorts, opens, or corrosion)
  • Poor connections or damaged connectors
  • Malfunctioning transmission control module (TCM)
  • Software issues or programming errors
  • Faulty transmission sensors
  • Internal transmission problems

Common misdiagnoses

  • Transmission fluid issues
  • Faulty transmission control module (TCM)
  • Wiring or connector problems
  • Faulty speed sensors
  • Malfunctioning valve body
  • Incorrectly diagnosed shift solenoids
  • Engine control module (ECM) issues
  • Mechanical transmission problems

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 Wiring and Connectors

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

  3. 3. Test the Normal/Performance Switch

    If accessible, test the normal/performance switch itself. Use a multimeter to check for continuity and ensure that the switch is functioning correctly. If the switch is faulty, it may need to be replaced

  4. 4. Check the Transmission Control Module (TCM)

    The TCM may be receiving incorrect signals from the normal/performance switch. Inspect the TCM for any signs of damage or malfunction. If necessary, reprogram or replace the TCM

  5. 5. Inspect the Transmission Fluid

    Low or dirty transmission fluid can cause various transmission issues. Check the fluid level and condition, and change it if necessary

  6. 6. Look for Mechanical Issues

    Inspect the transmission for any mechanical problems that could be affecting the performance switch circuit. This may include checking for issues with the valve body or other internal components

  7. 7. Perform a System Reset

    After addressing any issues found, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  8. 8. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the P0790 code

  9. 9. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission systems and can perform more advanced diagnostics. By following these steps, you can systematically identify and resolve the underlying issue causing the P0790 code