B1603 – Lamp Anti-Theft Indicator Circuit Failure

The ODBII code B1603 indicates a failure in the anti-theft indicator circuit, which may suggest a malfunction in the system that monitors the anti-theft lamp’s operation.

The severity of ODBII code B1603 is generally considered moderate.

Common Causes For: B1602 PATS Received Invalid Format Of Key-Code From Ignition Key Transponder

• Faulty anti-theft module
• Damaged wiring or connectors
• Short circuit in the circuit
• Open circuit in the circuit
• Malfunctioning lamp or bulb
• Faulty ignition switch
• Issues with the body control module (BCM)

Common misdiagnosis for B1603 Lamp Anti-Theft Indicator Circuit Failure

• Faulty anti-theft module
• Defective ignition switch
• Malfunctioning body control module (BCM)
• Wiring issues or shorts in the circuit
• Bad ground connections
• Faulty key fob or transponder
• Battery issues or low voltage
• Incorrectly programmed key or keyless entry system

Common Troubleshooting Steps

The OBD-II code B1603 indicates a “Lamp Anti-Theft Indicator Circuit Failure.” This code is typically associated with issues in the anti-theft system of a vehicle, particularly related to the indicator lamp that signals the status of the anti-theft system. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check the Vehicle’s Owner Manual: Refer to the vehicle’s service manual for specific information regarding the anti-theft system and the B1603 code. This can provide insights into the circuit layout and components involved.
• Inspect the Anti-Theft Indicator Lamp: Check the anti-theft indicator lamp on the dashboard. Ensure that it is functioning properly and not burned out. Replace it if necessary.
• Examine Wiring and Connectors: Inspect the wiring and connectors associated with the anti-theft system and the indicator lamp. Look for signs of damage, corrosion, or loose connections. Repair or replace any damaged components.
• Check the Anti-Theft Module: The anti-theft module may be malfunctioning. Test the module for proper operation. If you have access to a scan tool, you can check for additional codes that may indicate a problem with the module.
• Test the Circuit: Use a multimeter to test the circuit for continuity and proper voltage. Check for any shorts or open circuits that could be causing the failure.
• Inspect Fuses: Check the fuses related to the anti-theft system. A blown fuse can cause the indicator lamp to fail. Replace any blown fuses and retest the system.
• Reset the System: Sometimes, clearing the code and resetting the system can resolve the issue. Use an OBD-II scanner to clear the code and see if it returns after a test drive.
• Check for Other Codes: Look for any other related trouble codes that may provide additional context for the issue. Addressing other codes may resolve the B1603 code as well.
• Consult a Professional: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or an automotive electrician who specializes in anti-theft systems.
• Consider Software Updates: In some cases, a software update for the vehicle’s ECU may be necessary. Check with the manufacturer for any available updates that could resolve the issue. By following these troubleshooting steps, you should be able to identify and resolve the cause of the B1603 code. Always ensure safety precautions are taken when working on vehicle electrical systems.