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P0973 Shift Solenoid A Control Circuit Low

The OBD2 code P0973 indicates that there is a low voltage or an open circuit in the control circuit for Shift Solenoid A, which can affect the transmission's shifting performance

Definition

The OBD2 code P0973 indicates that there is a low voltage or an open circuit in the control circuit for Shift Solenoid A, which can affect the transmission's shifting performance

Common causes

  • Faulty shift solenoid A
  • Wiring issues (shorts or open circuits)
  • Poor electrical connections
  • Faulty transmission control module (TCM)
  • Low transmission fluid level
  • Contaminated transmission fluid
  • Internal transmission problems
  • Faulty PCM (Powertrain Control Module)

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Defective shift solenoid
  • Wiring issues or short circuits
  • Transmission fluid issues (low or contaminated fluid)
  • Faulty transmission range sensor
  • Incorrectly diagnosed transmission failure
  • Engine control module (ECM) issues
  • Poor electrical connections or grounds

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

  3. 3. Visually inspect the wiring and connectors associated with the shift solenoid. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to the wiring harness leading to the transmission and the solenoid itself

  5. 5. Test the Shift Solenoid

  6. 6. If accessible, test the shift solenoid for proper operation. This can often be done by measuring the resistance across the solenoid terminals with a multimeter. Refer to the vehicle's service manual for the specific resistance values

  7. 7. If the solenoid is faulty, it may need to be replaced

  8. 8. Check the Transmission Fluid

  9. 9. Ensure that the transmission fluid is at the correct level and in good condition. Low or dirty fluid can affect solenoid operation

  10. 10. If the fluid is dirty, consider performing a transmission fluid change

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

  12. 12. The TCM controls the operation of the shift solenoids. Check for any signs of damage or malfunction in the TCM

  13. 13. If possible, test the TCM for proper operation or consider reprogramming or replacing it if necessary

  14. 14. Check for Ground Issues

  15. 15. Ensure that the ground connections for the shift solenoid and TCM are secure and free of corrosion. Poor grounding can lead to low voltage readings

  16. 16. Perform a Voltage Test

  17. 17. With the ignition on (engine off), use a multimeter to check the voltage at the solenoid connector. Compare the reading to the specifications in the service manual

  18. 18. If the voltage is low, trace the circuit back to the TCM to identify any issues

  19. 19. Look for Short Circuits

  20. 20. Inspect the wiring for any signs of short circuits or grounding issues that could cause the low voltage reading

  21. 21. Clear Codes and Test Drive

  22. 22. After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  23. 23. Consult a Professional

  24. 24. If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician who has experience with transmission issues and OBD-II diagnostics. By following these steps, you should be able to identify the cause of the P0973 code and take appropriate action to resolve it