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P code powertrain Medium severity

P1873 Transmission Mechanical 4-Wheel Drive Axle Lock Lamp Circuit Short To Battery

The OBD2 code P1873 indicates a malfunction in the transmission's mechanical system related to the 4-wheel drive axle lock lamp circuit, specifically a short circuit to the battery, which may cause the axle lock...

Definition

The OBD2 code P1873 indicates a malfunction in the transmission's mechanical system related to the 4-wheel drive axle lock lamp circuit, specifically a short circuit to the battery, which may cause the axle lock indicator light to behave incorrectly

Common causes

  • Shorted wiring or connectors in the axle lock circuit
  • Faulty axle lock switch
  • Malfunctioning axle lock actuator
  • Damaged or corroded connectors
  • Faulty transmission control module (TCM)
  • Issues with the transfer case
  • Grounding problems in the circuit

Common misdiagnoses

  • Faulty axle lock switch
  • Defective transmission control module (TCM)
  • Wiring issues or shorts in the harness
  • Malfunctioning transfer case
  • Bad ground connections
  • Incorrectly installed or damaged axle components
  • Faulty vehicle speed sensor (VSS)
  • Issues with the four-wheel drive control module

Troubleshooting steps

  1. 1. Check the Code and Freeze Frame Data

    Use an OBD-II scanner to confirm the P1873 code and check for any additional codes that may provide more context

  2. 2. Review the freeze frame data to understand the conditions under which the code was set

  3. 3. Inspect the Wiring and Connectors

    Visually inspect the wiring harness and connectors related to the axle lock lamp circuit

  4. 4. Look for signs of damage, such as frayed wires, corrosion, or loose connections

  5. 5. Pay special attention to areas where the wiring may be exposed to heat or abrasion

  6. 6. Test the Axle Lock Lamp Circuit

    Use a multimeter to check for continuity in the axle lock lamp circuit

  7. 7. Measure the voltage at the axle lock lamp connector with the ignition on and the vehicle in the appropriate mode (4WD engaged if applicable)

  8. 8. If the voltage is present when it shouldn’t be, there may be a short to battery

  9. 9. Check the Axle Lock Switch

    Inspect the axle lock switch for proper operation. Ensure it is not stuck or malfunctioning

  10. 10. Test the switch for continuity and proper function using a multimeter

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

    Check for any issues with the TCM that could affect the axle lock circuit

  12. 12. Ensure that the TCM is receiving the correct signals from the axle lock switch

  13. 13. Inspect the 4WD System Components

    Check the 4WD system components, including the transfer case and any related actuators or solenoids

  14. 14. Ensure that all components are functioning correctly and that there are no mechanical issues

  15. 15. Clear the Code and Test Drive

    After performing the above checks and repairs, clear the code using the OBD-II scanner

  16. 16. Take the vehicle for a test drive to see if the code reappears

  17. 17. Follow any manufacturer-specific troubleshooting steps

  18. 18. Seek Professional Help

    If you are unable to resolve the issue after following these steps, consider seeking help from a qualified mechanic or automotive technician who has experience with transmission and 4WD systems.Additional Tips: - Always ensure that the vehicle is safely supported and that you take necessary precautions when working on electrical systems. - Document any changes or repairs made during the troubleshooting process for future reference. By following these steps, you should be able to identify the cause of the P1873 code and take appropriate action to resolve the issue