B1794 Low Beam Circuit Malfunction
The B1794 code indicates that the Body Control Module (BCM) has detected a fault in the low beam headlamp circuit. This typically means the BCM has identified an open circuit, short to ground, or short to battery voltage in the low beam power supply wiring, preventing the low beams from operating correctly.
1. Commonly Affected Makes
2. Most Common Causes
- Blown or incorrect low beam bulb
- Open, short to ground, or short to battery in the low beam circuit wiring
- Damaged, corroded, or loose connector at the headlamp or BCM
- Faulty low beam relay (if equipped)
- Defective Body Control Module (BCM)
3. Symptoms You Will Notice
- Low beam headlights inoperative
- Low beam headlights flickering or intermittent
- Warning light on dashboard (e.g., headlight indicator)
4. Step-by-Step Diagnosis
Check for blown fuses related to the low beam circuit.
Inspect low beam bulbs for damage or incorrect type.
Test voltage and ground at the low beam bulb connector using a multimeter.
Inspect wiring and connectors for corrosion, damage, or loose connections.
If wiring and bulbs are good, test the low beam relay (if applicable) and BCM output.
5. Frequently Asked Questions
Is it safe to drive?▼
Driving at night or in low visibility conditions is not safe without low beams. During daytime, you can drive cautiously, but have the issue repaired promptly.
How much does it cost to fix?▼
Costs vary: a bulb replacement is $15–$50; wiring repairs $50–$200; BCM replacement $200–$600 plus programming. Expect $100–$400 at a shop.