B1577: Parking Light Circuit Short to Battery
The Body Control Module (BCM) or Smart Junction Box (SJB) has detected a short to battery voltage on the parking light input circuit. This means voltage is present on the control or power circuit when the module has not commanded the lights on, preventing the parking lights from turning off properly and potentially draining the battery.
1. Commonly Affected Makes
2. Most Common Causes
- Wiring in the parking light circuit shorted to battery positive (B+)
- Faulty parking light relay with stuck contacts
- Internally damaged BCM or SJB module
- Corroded connectors or internal bridges in the wiring harness
- Defective headlamp switch sending an incorrect signal
3. Symptoms You Will Notice
- Parking lights remain on even with the switch off
- Battery drains overnight or after short periods
4. Step-by-Step Diagnosis
Check for battery voltage on the parking light circuit with the lights off using a multimeter.
Inspect the parking light relay for stuck contacts; replace if faulty.
Test the headlamp switch for proper operation and signal output.
Examine wiring and connectors for corrosion, damage, or shorts to B+.
If all else is normal, suspect a failed BCM/SJB and perform module testing.
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but the parking lights may stay on and drain the battery. It's best to diagnose and repair promptly to avoid a dead battery.
How much does it cost to fix?▼
Typically $100–$400, depending on whether it's a simple relay/switch replacement or a BCM repair.