B1802 – Lamp Turn Signal Rear Output Circuit Failure

The ODBII code B1802 indicates a malfunction in the rear turn signal output circuit, suggesting a failure in the circuit responsible for activating the rear turn signal lights.

The severity of ODBII code B1802 is moderate.

Common Causes For: B1801 Lamp Turn Signal Front Output Circuit Short To Ground

• Faulty turn signal bulb
• Damaged wiring or connectors
• Short circuit in the circuit
• Open circuit in the circuit
• Faulty turn signal relay
• Malfunctioning body control module (BCM)
• Corroded or loose connections
• Faulty ground connection

Common misdiagnosis for B1802 Lamp Turn Signal Rear Output Circuit Failure

• Faulty turn signal bulb
• Bad turn signal switch
• Damaged wiring or connectors
• Faulty body control module (BCM)
• Incorrectly installed or loose bulb socket
• Grounding issues
• Faulty relay
• Corroded terminals

Common Troubleshooting Steps

The OBD-II code B1802 indicates a “Lamp Turn Signal Rear Output Circuit Failure.” This code typically relates to issues with the rear turn signal circuit in a vehicle. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Visual Inspection:
• Check the rear turn signal bulbs for any signs of damage or burnout. Replace any faulty bulbs.
• Inspect the bulb sockets for corrosion, dirt, or damage. Clean or replace as necessary.
• Examine the wiring and connectors leading to the rear turn signal for any signs of fraying, breaks, or corrosion.
• Check Fuses:
• Locate the fuse box and check the fuses related to the turn signal circuit. Replace any blown fuses.
• Test the Turn Signal Switch:
• The turn signal switch on the steering column can sometimes fail. Test the switch for proper operation using a multimeter or by checking for continuity.
• Use a Multimeter:
• With the turn signal activated, use a multimeter to check for voltage at the turn signal socket. If there is no voltage, trace the wiring back to the turn signal switch and check for continuity.
• Check for ground at the turn signal socket. A poor ground connection can cause the circuit to fail.
• Inspect the Body Control Module (BCM):
• The BCM controls various lighting functions, including turn signals. If all other components check out, the BCM may be faulty. Use a scan tool to check for any additional codes or issues related to the BCM.
• Check for Short Circuits:
• Inspect the wiring for any signs of short circuits, especially in areas where the wiring may rub against metal or other components.
• Clear Codes and Test:
• After performing repairs, clear the OBD-II codes using a scan tool and take the vehicle for a test drive to see if the code returns.
• Consult Wiring Diagrams:
• If the issue persists, consult the vehicle’s wiring diagrams to trace the circuit and identify any other components that may be involved.
• Professional Diagnosis:
• If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic who can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the issue related to the B1802 code.