B1794 – Lamp Headlamp Low-Beam Circuit Failure

The ODBII code B1794 indicates a failure in the low-beam headlamp circuit, which may involve issues such as a malfunctioning bulb, wiring problems, or a faulty headlamp control module.

The severity of ODBII code B1794 is moderate.

Common Causes For: B1793 Autolamp Sensor Input Circuit Short To Ground

• Faulty low-beam headlamp bulb
• Damaged wiring or connectors
• Failed headlamp relay
• Malfunctioning body control module (BCM)
• Corroded or loose ground connections
• Blown fuse in the headlamp circuit
• Faulty switch or control for the headlamps

Common misdiagnosis for B1794 Lamp Headlamp Low-Beam Circuit Failure

• Faulty headlight bulb
• Bad headlight relay
• Wiring issues or shorts in the circuit
• Faulty body control module (BCM)
• Defective headlight switch
• Ground connection problems
• Incorrectly installed or damaged connectors

Common Troubleshooting Steps

The OBD-II code B1794 indicates a “Lamp Headlamp Low-Beam Circuit Failure.” This code typically relates to issues with the low-beam headlight circuit, which can be caused by various factors. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Visual Inspection:
• Check the headlight bulbs: Ensure that the low-beam bulbs are not burned out or damaged.
• Inspect the wiring: Look for any frayed, damaged, or corroded wires in the headlight circuit.
• Examine the connectors: Ensure that all connectors are secure and free of corrosion.
• Check Fuses:
• Locate the fuse box and check the fuses related to the headlight circuit. Replace any blown fuses.
• Test the Headlight Switch:
• Verify that the headlight switch is functioning correctly. A faulty switch can prevent the low beams from operating.
• Measure Voltage:
• Use a multimeter to check for voltage at the headlight connector. If there is no voltage, trace the circuit back to find where the break or fault may be.
• Inspect the Relay:
• If your vehicle uses a relay for the low-beam headlights, check the relay for proper operation. Swap it with a similar relay (if available) to see if that resolves the issue.
• Check Ground Connections:
• Ensure that the ground connections for the headlight circuit are clean and secure. A poor ground can cause circuit failures.
• Scan for Additional Codes:
• Use an OBD-II scanner to check for any additional trouble codes that may provide more context for the issue.
• Test the Body Control Module (BCM):
• If all other components check out, the issue may lie within the BCM. Testing or reprogramming the BCM may be necessary.
• Consult Wiring Diagrams:
• Refer to the vehicle’s wiring diagrams to understand the circuit layout and identify any potential issues.
• 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 cause of the B1794 code. Always remember to take necessary safety precautions when working with electrical systems in vehicles.