* Parking Brake Engaged: The most obvious reason. Make absolutely sure the parking brake is fully released. Sometimes, a cable can bind or a mechanism can stick, leaving the brake partially engaged even if the lever feels released.
* Brake Pedal Switch: This switch tells the system when the brake pedal is pressed. If it's faulty, it might constantly signal that the brakes are engaged, even when they aren't. This is a common culprit.
* Brake Fluid Level: A low brake fluid level often triggers the light. Check your brake fluid reservoir (usually a clear plastic container) and add fluid if needed. *However, adding fluid without identifying the leak is a temporary fix and could mask a serious problem.*
* Brake Light Switch: This is distinct from the brake pedal switch. A faulty brake light switch can cause the brake lights and the emergency brake light to remain on.
* Wiring Issues: A short circuit or a damaged wire in the brake light circuit can cause the light to stay on. This might involve the wiring harness running to the rear lights, the switch, or elsewhere in the system.
* Brake System Sensor Issues (ABS, etc.): More advanced systems like the Anti-lock Braking System (ABS) might have sensors that contribute to the warning light. A faulty sensor could trigger the light, even if the brake system itself is fine.
* Faulty Combination Switch: This is a multi-function switch located on the steering column. It can affect various things, including the turn signals, windshield wipers, and cruise control; a problem in this switch can sometimes trigger the emergency brake light.
* Grounding Issue: A poor ground connection somewhere in the electrical system can cause erratic behavior, including the brake lights.
Troubleshooting Steps:
1. Check the Parking Brake: This is the first and easiest thing to check. Ensure it's completely released. Try gently rocking the vehicle back and forth to see if it releases completely.
2. Check Brake Fluid Level: Inspect the brake fluid reservoir. Low fluid is a serious problem and needs immediate attention.
3. Inspect Brake Lights: Are the brake lights themselves working properly? If they're also constantly on, that points towards the brake light switch or wiring.
4. Get it Diagnosed: The most reliable way to diagnose the issue is to take your Suburban to a mechanic or use an OBD-II scanner. The scanner might provide codes that pinpoint the exact problem. A qualified mechanic can test all the components and identify the root cause.
Ignoring a constantly illuminated emergency brake light is dangerous. It could indicate a serious problem with your braking system. Have it checked as soon as possible.
