Left Rear Brake Light Circuit Malfunction
The Body Control Module (BCM) has detected a fault in the left rear brake light circuit. This means the BCM sees a discrepancy between the commanded state (on/off) and the actual monitored circuit voltage or current. The issue is typically caused by an open circuit, short to ground, or short to battery voltage in the wiring or bulb.
1. Commonly Affected Makes
2. Most Common Causes
- Blown or incorrect left rear brake light bulb
- Open circuit in the signal wire between the BCM and left rear light
- Short to ground in the left brake light circuit
- Short to battery voltage in the left brake light circuit
- Damaged, corroded, or loose connector at the tail light or BCM
- Internal failure of the Body Control Module (BCM)
3. Symptoms You Will Notice
- Left rear brake light inoperative or dim
- Brake light warning on the dashboard
4. Step-by-Step Diagnosis
Check the left rear brake light bulb for being burned out or wrong type
Inspect the wiring and connectors for damage, corrosion, or looseness
Test for voltage and ground at the bulb socket with brake pedal pressed
Check for shorts or opens in the circuit between the BCM and the light
If all else is fine, suspect a faulty BCM and perform further diagnostics
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but it is not recommended because a non-functional brake light reduces safety and may lead to a traffic citation. Have it repaired soon.
How much does it cost to fix?▼
Typically $20-$100 for a bulb or simple wiring repair; $200-$600 if the BCM needs replacement.