WOMS
P code powertrain Medium severity

P0956 ASM Mode Circuit Range/Performance

The OBD2 code P0956 indicates a problem with the ASM (Automatic Shift Management) mode circuit, specifically related to its range or performance, suggesting that the system is not operating within the expected parameters

Definition

The OBD2 code P0956 indicates a problem with the ASM (Automatic Shift Management) mode circuit, specifically related to its range or performance, suggesting that the system is not operating within the expected parameters

Common causes

  • Faulty transmission control module (TCM)
  • Wiring issues or damaged connectors
  • Faulty ASM (Automatic Shift Management) system components
  • Low transmission fluid level or poor fluid condition
  • Malfunctioning sensors related to the transmission
  • Software issues or programming errors in the TCM
  • Mechanical issues within the transmission system

Common misdiagnoses

  • Transmission control module (TCM) failure
  • Faulty wiring or connectors
  • Incorrect transmission fluid level or type
  • Malfunctioning transmission sensors
  • Issues with the clutch or gear engagement
  • Engine control module (ECM) problems
  • Software or calibration issues in the TCM
  • 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. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors related to the ASM mode circuit. Look for signs of damage, corrosion, or loose connections that could affect the circuit's performance

  3. 3. Test the ASM Circuit

    Use a multimeter to test the voltage and ground at the ASM circuit connector. Compare the readings to the specifications in the vehicle's service manual

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

    The TCM is responsible for managing the transmission's operation. Ensure that it is functioning correctly and that there are no issues with its programming or connections

  5. 5. Inspect the Transmission Fluid

    Low or contaminated transmission fluid can cause performance issues. Check the fluid level and condition, and replace it if necessary

  6. 6. Examine the Shift Solenoids

    The shift solenoids control the flow of transmission fluid and can affect shifting performance. Test the solenoids for proper operation and replace any that are faulty

  7. 7. Look for Mechanical Issues

    Inspect the transmission for any mechanical problems, such as worn components or internal damage, that could affect shifting performance

  8. 8. Perform a Reset

    Sometimes, resetting the TCM by disconnecting the battery for a few minutes can clear temporary glitches. However, this should be done with caution, as it may also erase other learned parameters

  9. 9. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P0956 code for your specific vehicle make and model. Manufacturers may have issued guidance or fixes for known issues

  10. 10. Professional Diagnosis

    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 issues and can perform more advanced diagnostics. Always refer to the vehicle's service manual for specific procedures and specifications related to your particular make and model