WOMS
B code body Medium severity

B1304 Accessory Delay Relay Coil Circuit Short To Battery

The OBD2 code B1304 indicates a malfunction in the accessory delay relay coil circuit, specifically a short circuit to the battery, which can prevent the relay from functioning properly

Definition

The OBD2 code B1304 indicates a malfunction in the accessory delay relay coil circuit, specifically a short circuit to the battery, which can prevent the relay from functioning properly

Common causes

  • Shorted wiring or connectors in the accessory delay relay circuit
  • Faulty accessory delay relay
  • Corroded or damaged electrical connections
  • Malfunctioning body control module (BCM)
  • Incorrectly installed aftermarket accessories
  • Grounding issues in the circuit

Common misdiagnoses

  • Faulty accessory delay relay
  • Shorted wiring harness
  • Defective body control module (BCM)
  • Malfunctioning ignition switch
  • Battery issues or poor connections
  • Faulty fuses or relay sockets
  • Incorrectly installed aftermarket accessories

Troubleshooting steps

  1. 1. Check the Vehicle's Battery and Charging System

    Inspect the Battery: Ensure the battery is in good condition, fully charged, and terminals are clean and tight

  2. 2. Test the Charging System

    Use a multimeter to check the voltage output of the alternator while the engine is running. It should typically be between 13.5 to 14.5 volts

  3. 3. Inspect the Accessory Delay Relay

    Locate the Relay: Find the accessory delay relay in the fuse box or relay panel (refer to the vehicle’s service manual for the exact location)

  4. 4. Check for Damage

    Inspect the relay for any signs of damage, corrosion, or burnt contacts

  5. 5. Test the Relay

    Swap the relay with a similar one (if available) to see if the problem persists

  6. 6. Examine Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring in the accessory delay relay circuit

  7. 7. Check Connectors

    Ensure all connectors are secure and free of corrosion. Pay special attention to ground connections

  8. 8. Use a Multimeter

    Test the continuity of the wiring from the relay to the battery and other components in the circuit

  9. 9. Check for Short Circuits

    Inspect for Shorts: Use a multimeter to check for shorts to ground or battery voltage in the accessory delay relay circuit

  10. 10. Isolate the Circuit

    Disconnect components one at a time to identify if a specific part is causing the short

  11. 11. Scan for Additional Codes

    Use an OBD-II Scanner: Check for any other trouble codes that may provide additional context or indicate related issues

  12. 12. Clear Codes

    After repairs, clear the codes and see if the B1304 code returns

  13. 13. Inspect Related Components

    Check Fuses: Inspect any fuses related to the accessory delay relay circuit for continuity and replace if necessary

  14. 14. Look for Other Malfunctions

    Sometimes, other components like the body control module (BCM) or ignition switch can cause issues in the circuit

  15. 15. Consult the Service Manual

    Refer to Wiring Diagrams: Use the vehicle’s service manual to understand the circuit layout and identify any specific components that may be involved

  16. 16. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or automotive technician who can perform more advanced diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1304 code. Always ensure safety precautions are taken when working with the vehicle's electrical system