B1555 – Ignition Run/Start Circuit Failure

The ODBII code B1555 indicates a failure in the ignition run/start circuit, which may involve issues with the ignition switch, wiring, or related components affecting the vehicle’s ability to start or run properly.

The severity of ODBII code B1555 Ignition Run/Start Circuit Failure is typically considered moderate to severe.

Common Causes For: B1554 Decklid Release Circuit Short To Ground

• Faulty ignition switch
• Damaged wiring or connectors in the ignition circuit
• Failed powertrain control module (PCM)
• Short circuit in the ignition run/start circuit
• Poor ground connection
• Malfunctioning relay
• Issues with the body control module (BCM)

Common misdiagnosis for B1555 Ignition Run/Start Circuit Failure

• Faulty ignition switch
• Bad battery connections
• Defective starter motor
• Malfunctioning fuel pump
• Wiring issues or shorts in the ignition circuit
• Faulty body control module (BCM)
• Defective relay or fuse
• Issues with the anti-theft system
• Faulty key or key fob
• Problems with the engine control module (ECM)

Common Troubleshooting Steps

The OBD-II code B1555 indicates an “Ignition Run/Start Circuit Failure.” This code is typically associated with issues in the ignition system, particularly in the circuit that controls the ignition run/start function. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check the Battery:
• Ensure the battery is fully charged and in good condition. A weak battery can cause various electrical issues.
• Inspect Fuses:
• Check the fuses related to the ignition system. A blown fuse can interrupt the circuit and trigger the code.
• Examine Wiring and Connectors:
• Inspect the wiring and connectors associated with the ignition system for any signs of damage, corrosion, or loose connections. Pay special attention to the ignition switch and any related harnesses.
• Test the Ignition Switch:
• The ignition switch itself may be faulty. Use a multimeter to test the switch for continuity in the run and start positions.
• Check for Ground Issues:
• Ensure that all ground connections related to the ignition system are secure and free of corrosion. Poor grounding can lead to circuit failures.
• Scan for Additional Codes:
• Use an OBD-II scanner to check for any other related trouble codes that may provide more context for the issue.
• Inspect the PCM (Powertrain Control Module):
• In some cases, the PCM may be at fault. Check for any software updates or known issues with the PCM for your specific vehicle model.
• Test the Ignition Relay:
• If your vehicle uses an ignition relay, test it to ensure it is functioning properly. A faulty relay can prevent the ignition system from operating correctly.
• Check for Short Circuits:
• Look for any short circuits in the ignition wiring that could be causing the failure. This may require a more in-depth inspection of the wiring harness.
• Consult Vehicle-Specific Repair Manuals:
• Refer to the vehicle’s service manual for specific diagnostic procedures and wiring diagrams related to the ignition system. 1
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or technician who has experience with your vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the B1555 code. Always remember to take necessary safety precautions when working on vehicle electrical systems.