* Brake Light Switch: This is the most likely culprit. The brake light switch is a small component that tells the car when the brake pedal is pressed. If it's faulty, it might be stuck in the "pressed" position, even when the pedal is released. This is often caused by wear and tear.
* Faulty Brake Pedal Position Sensor: Similar to the brake light switch, a malfunctioning sensor can send incorrect signals, keeping the brake lights illuminated.
* Short Circuit in the Wiring: A short circuit in the wiring harness leading to the brake lights can cause them to remain on. This could be due to damaged wires, frayed insulation, or corrosion.
* Central Electrical Module (CEM) or Body Control Module (BCM) Issue: In more complex cases, a problem with the car's computer system (CEM or BCM) can cause unintended activation of the brake lights. This is less common but possible.
* Faulty Tail Light Assemblies: While less likely to keep the lights *constantly* on, a short or other internal fault within a tail light assembly could be causing a drain on the system.
* Parking Brake Engaged: Though unlikely to stay on continuously after the car is completely off, ensure the parking brake is fully released.
What to do:
1. Check the obvious: First, make sure the parking brake isn't engaged.
2. Visual Inspection: Carefully examine the brake light switch and the wiring harness leading to the brake lights for any signs of damage, corrosion, or loose connections.
3. Battery Drain: Leaving the brake lights on will drain your battery. If they're on, disconnect the negative terminal of the battery to prevent a complete discharge.
4. Professional Diagnosis: If you can't find the problem yourself, take your Envoy to a qualified mechanic or auto electrician. They have the tools and expertise to diagnose the problem accurately and safely. They can use a diagnostic scanner to check for error codes, which can pinpoint the exact cause.
Ignoring the problem will eventually drain your battery, leaving you stranded. It's important to address this issue as soon as possible.
