B1302 – Accessory Delay Relay Coil Circuit Failure

The ODBII code B1302 indicates a failure in the accessory delay relay coil circuit, which may affect the operation of accessories that remain powered after the ignition is turned off.

The severity of ODBII code B1302 is generally considered moderate.

Common Causes For: B1301 Power Door Lock Circuit Open

• Faulty accessory delay relay
• Damaged wiring or connectors
• Short circuit in the relay circuit
• Open circuit in the relay circuit
• Malfunctioning body control module (BCM)
• Corroded terminals or connections
• Faulty ignition switch
• Battery issues or low voltage

Common misdiagnosis for B1302 Accessory Delay Relay Coil Circuit Failure

• Faulty battery
• Bad ground connections
• Malfunctioning ignition switch
• Defective body control module (BCM)
• Wiring issues or shorts in the circuit
• Faulty accessory delay relay
• Issues with other relays or fuses in the system

Common Troubleshooting Steps

The OBD-II code B1302 indicates a problem with the accessory delay relay coil circuit. This code is often related to the vehicle’s electrical system, particularly the circuits that control the accessory delay feature, which keeps certain electrical components powered for a short time after the ignition is turned off. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check the Vehicle’s Battery: Ensure the battery is fully charged and in good condition. A weak or failing battery can cause various electrical issues.
• Inspect Fuses: Check the fuses related to the accessory delay relay and other related circuits. Replace any blown fuses.
• Examine the Relay: Locate the accessory delay relay in the fuse box or relay panel. Inspect it for any signs of damage or corrosion. If necessary, swap it with a similar relay to see if the problem persists.
• Inspect Wiring and Connectors: Check the wiring and connectors associated with the accessory delay relay circuit for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components.
• Test the Relay Circuit: Use a multimeter to test the relay coil circuit for continuity and proper voltage. Ensure that the relay is receiving the correct voltage when the ignition is in the appropriate position.
• Check for Short Circuits: Inspect the circuit for any short circuits that may be causing the relay to fail. This can include checking for damaged insulation or pinched wires.
• Scan for Additional Codes: Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues.
• Inspect the Body Control Module (BCM): If all other components check out, the issue may lie within the Body Control Module (BCM). Inspect the BCM for any faults or failures, as it controls many accessory functions.
• Consult Wiring Diagrams: Refer to the vehicle’s service manual for wiring diagrams to understand the circuit layout and identify any potential issues.
• Clear the Code and Test Drive: After performing repairs, clear the trouble code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.1
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1302 code.