WOMS
C code chassis Medium severity

C1742 Rear Sounder Circuit Failure

The OBD2 code C1742 indicates a failure in the rear sounder circuit, which is typically related to the vehicle's alarm or warning system

Definition

The OBD2 code C1742 indicates a failure in the rear sounder circuit, which is typically related to the vehicle's alarm or warning system

Common causes

  • Faulty rear sounder
  • Damaged wiring or connectors
  • Short circuit in the circuit
  • Open circuit in the circuit
  • Corroded connectors
  • Faulty control module
  • Poor ground connection

Common misdiagnoses

  • Faulty rear sounder/speaker
  • Wiring issues or shorts in the circuit
  • Faulty body control module (BCM)
  • Incorrectly diagnosed as a brake system issue
  • Misinterpretation as a general electrical fault
  • Battery or power supply problems
  • Faulty connectors or terminals in the circuit

Troubleshooting steps

  1. 1. Check the Vehicle's Manual

    Refer to the vehicle's service manual for specific information related to the C1742 code, including wiring diagrams and component locations

  2. 2. Visual Inspection

  3. 3. Inspect the wiring and connectors associated with the rear sounder. Look for any signs of damage, corrosion, or loose connections

  4. 4. Check the rear sounder itself for physical damage

  5. 5. Test the Rear Sounder

  6. 6. If accessible, disconnect the rear sounder and test it with a multimeter to ensure it is functioning correctly. You can also apply direct power to see if it activates

  7. 7. If the sounder does not work when powered directly, it may need to be replaced

  8. 8. Check for Faulty Connections

  9. 9. Ensure that all connectors are secure and free of corrosion. Clean any corroded terminals and reconnect them

  10. 10. Check for any broken or frayed wires in the circuit

  11. 11. Inspect the Alarm/Immobilizer System

  12. 12. If the vehicle has an aftermarket alarm or immobilizer system, ensure it is installed correctly and not interfering with the rear sounder circuit

  13. 13. Check for any fault codes related to the alarm system that may provide additional insight

  14. 14. Scan for Additional Codes

  15. 15. Use an OBD-II scanner to check for any other related trouble codes that may help identify the issue

  16. 16. Clear the codes and see if the C1742 code returns after a test drive

  17. 17. Check the Power and Ground

  18. 18. Use a multimeter to check for proper voltage at the rear sounder connector. Ensure that the sounder is receiving power and ground as expected

  19. 19. If there is no power or ground, trace the circuit back to the source to identify any breaks or shorts

  20. 20. Inspect the Control Module

  21. 21. If all other components check out, the issue may lie within the vehicle's control module (BCM or PCM). Check for software updates or known issues related to the module

  22. 22. Consult Technical Service Bulletins (TSBs)

  23. 23. Look for any TSBs related to the C1742 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

  24. 24. Professional Diagnosis

  25. 25. If the problem persists after performing these steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose the issue more effectively. By following these steps, you should be able to identify and resolve the cause of the C1742 code