B1799 – Lamp Turn Signal Front Output Circuit Open

The ODBII code B1799 indicates that there is an open circuit in the front turn signal output, meaning the vehicle’s system is not detecting a proper connection or signal from the front turn signal lamp.

The severity of ODBII code B1799 is moderate.

Common Causes For: B1798 Lamp Turn Signal Front Output Circuit Failure

• Open circuit in the turn signal wiring
• Faulty turn signal bulb
• Defective turn signal relay
• Poor ground connection
• Damaged or corroded connectors
• Faulty body control module (BCM)
• Short circuit in the wiring harness

Common misdiagnosis for B1799 Lamp Turn Signal Front Output Circuit Open

• Faulty turn signal switch
• Bad wiring or connections
• Defective body control module (BCM)
• Malfunctioning relay
• Burnt-out bulbs
• Incorrectly installed bulbs
• Grounding issues
• Faulty fuse

Common Troubleshooting Steps

The OBD-II code B1799 indicates a problem with the front turn signal output circuit, specifically that there is an open circuit. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information about the turn signal circuit and wiring diagrams.
• Visual Inspection:
• Inspect the front turn signal bulbs to ensure they are not burned out or damaged.
• Check the bulb sockets for corrosion or damage.
• Look for any visible damage to the wiring harness, connectors, or terminals related to the turn signal circuit.
• Test the Bulbs:
• Remove the turn signal bulbs and test them with a multimeter to ensure they are functioning properly.
• Replace any faulty bulbs.
• Check the Fuses:
• Locate the fuse box and check for any blown fuses related to the turn signal circuit. Replace any blown fuses.
• Inspect the Wiring and Connectors:
• Follow the wiring from the turn signal bulbs back to the control module. Look for any signs of wear, fraying, or disconnection.
• Ensure that all connectors are securely attached and free of corrosion.
• Test the Turn Signal Relay:
• If applicable, test the turn signal relay to ensure it is functioning correctly. You can swap it with a similar relay in the fuse box to see if the problem persists.
• Check for Ground Issues:
• Ensure that the ground connection for the turn signal circuit is secure and free of corrosion. A poor ground can cause an open circuit.
• Scan for Additional Codes:
• Use an OBD-II scanner to check for any additional trouble codes that may provide more context for the issue.
• Perform a Continuity Test:
• Use a multimeter to perform a continuity test on the wiring from the turn signal switch to the bulbs. This will help identify any breaks in the circuit.
• Inspect the Turn Signal Switch:
• If all other components check out, the turn signal switch itself may be faulty. Test or replace the switch if necessary. 1
• 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. If you are not comfortable performing these steps or if the issue persists after troubleshooting, it may be best to consult a professional mechanic for further diagnosis and repair.