WOMS
P code powertrain Medium severity

P1738 Shift Time Error

The OBD2 code P1738 indicates a "Shift Time Error," which means there is a discrepancy in the expected time for a gear shift in the transmission system, potentially signaling a problem with the transmission control...

Definition

The OBD2 code P1738 indicates a "Shift Time Error," which means there is a discrepancy in the expected time for a gear shift in the transmission system, potentially signaling a problem with the transmission control module or related components

Common causes

  • Faulty transmission control module (TCM)
  • Malfunctioning speed sensors
  • Wiring issues or damaged connectors
  • Low transmission fluid levels
  • Transmission fluid contamination
  • Internal transmission problems
  • Incorrectly adjusted or faulty throttle position sensor (TPS)
  • Software issues or outdated firmware in the TCM

Common misdiagnoses

  • Transmission fluid issues
  • Faulty transmission control module (TCM)
  • Wiring or connector problems
  • Faulty speed sensors
  • Incorrectly calibrated transmission
  • Mechanical transmission issues
  • Engine control module (ECM) problems
  • Throttle position sensor 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 Transmission Fluid

    Fluid Level: Ensure that the transmission fluid is at the correct level. Low fluid can cause shifting issues

  3. 3. Fluid Condition

    Check the condition of the fluid. It should be a bright red color and should not smell burnt. If it is dark or has a burnt smell, consider changing the fluid

  4. 4. Examine Wiring and Connectors

    Inspect the wiring and connectors related to the transmission and TCM for any signs of damage, corrosion, or loose connections. Repair or replace as necessary

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

    Ensure that the TCM is functioning properly. If there are issues with the TCM, it may need to be reprogrammed or replaced

  6. 6. Inspect Sensors

    Check the input and output speed sensors, as well as the throttle position sensor. These sensors play a crucial role in the transmission's shifting behavior. Test them for proper operation and replace if faulty

  7. 7. Test the Transmission

    If the above steps do not resolve the issue, consider having the transmission tested. This may involve checking for mechanical issues, such as worn clutches or bands

  8. 8. Check for Software Updates

    Sometimes, manufacturers release software updates for the TCM. Check with the dealership or a qualified technician to see if any updates are available for your vehicle

  9. 9. Clear Codes and Test Drive

    After performing any repairs or adjustments, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears

  10. 10. Consult a Professional

    If the issue persists after performing these troubleshooting steps, it may be best to consult a professional mechanic or transmission specialist for a more in-depth diagnosis.Additional Notes: - Always refer to the vehicle's service manual for specific procedures and specifications related to your make and model. - Safety first: Ensure the vehicle is in a safe position and properly supported if you are working underneath it. By following these steps, you can systematically diagnose and address the cause of the P1738 code