The warning indicates the center/high mounted brake light (the third brake light) isn’t functioning properly and should be inspected. This lights up because the vehicle’s monitoring system detected a fault in that circuit, which can reduce visibility to drivers behind you.
In practical terms, the message is a prompt to assess the third brake light—usually mounted high on the rear window or the trunk lid—for issues such as a burnt-out bulb, a faulty connection, or a more complex electrical problem. Addressing it promptly helps maintain safe braking signaling for following drivers, particularly in heavy traffic or at night.
What is the high-mounted brake light and why it matters
The high-mounted brake light, also known as the center high mount stop lamp (CHMSL), is designed to provide an additional, higher-placed cue that you are braking. It complements the standard brake lights and can improve visibility to drivers who are farther back or in long sightlines, reducing the risk of rear-end collisions.
Common causes of the warning
Before taking action, it helps to know what problems typically trigger the message. The list below covers the most frequent culprits, from simple to more complex issues.
- Burnt-out bulb in the CHMSL or a failed LED module
- Faulty bulb socket, wiring, or corroded connections
- Blown fuse or a problem with the CHMSL circuit in the fuse box
- Faulty brake light switch or control module that governs the CHMSL
- Moisture intrusion or condensation inside the light assembly
- Damaged wiring harness or loose connectors near the rear of the vehicle
- Aftermarket modifications interfering with the CHMSL circuit
- Faulty CHMSL unit itself, especially in older vehicles
Understanding these causes helps drivers decide whether the issue is a quick, DIY fix or one that requires a shop visit. If the light appears to be completely dark when braking, start with the simplest checks before moving to more involved diagnostics.
How to diagnose and fix the problem
The following steps outline a practical approach to diagnosing and resolving a CHMSL warning. Use them in order, stopping if you locate and fix the fault early.
- Test the light by having a helper press the brake pedal while you observe the CHMSL to confirm whether it lights up with braking.
- Inspect the CHMSL bulb or LED module for signs of failure or damage; replace a burnt bulb or faulty LED unit with the correct part for your vehicle model.
- Check the fuses and relays related to the CHMSL circuit in the vehicle’s fuse box; replace any blown fuse with the correct amperage fuse.
- Examine the wiring and connectors at the CHMSL for looseness, corrosion, or damaged insulation; reseat connectors and clean corrosion if present.
- Look for moisture inside the light housing and dry or replace the seal if water intrusion is suspected.
- Assess for aftermarket wiring or modifications that might affect the CHMSL circuit and revert or rewire as needed.
- If the problem persists after these checks, a professional diagnostic using a scan tool or inspection of the body control module may be necessary.
After performing these steps, retest the CHMSL to confirm whether the warning clears and the light functions correctly. If you are unsure or uncomfortable with electrical work, it is wise to consult a qualified technician.
Safety considerations when you see the warning
While the standard brake lights continue to function in many cases, a failing CHMSL reduces the redundancy of braking signals for drivers behind you. Drive with extra caution, allow more following distance, and seek repair promptly to restore full signaling capability.
What to do next
Once you’ve identified the likely cause, decide on a repair plan. Simple bulb replacements are often quick and inexpensive, while wiring or control-module issues may require professional service. Keeping the CHMSL in good working order is part of regular vehicle maintenance and safety checks.
Summary
The message Check High Mounted Brake Light means your third brake light isn’t functioning properly and should be inspected. Common causes include a burnt-out bulb or LED, faulty socket or wiring, blown fuses, moisture, and in some cases a faulty control module. A structured diagnostic—starting with a visual check and moving through bulbs, fuses, connectors, and moisture—usually resolves the issue. If the problem persists, professional inspection is recommended to ensure safe braking signaling for all road users.
How much to replace a high mounted brake light?
The cost of aftermarket third brake light bulbs may range between $50 and $250 for parts alone. Several factors affect pricing, such as brand, warranty, color or finish, light source, and set inclusions. Labor may cost you an additional $25 to $75 depending on the rates in your area.
What does it mean when my car says check high mounted brake light?
It may be an intermittent. Problem or it may pop up any time you're pressing the brake pedal the simple solution is to replace.
How to change high mounted brake light on Kia Forte?
Size is 7506. If you want to upgrade to LED bulb check the link in description. Let's get the new bulb put it back in the bulb holder. And then push it down. And twist your right let it go.
Is it safe to drive with the check brake light on?
BRAKE WARNING LIGHT = BRAKE SYSTEM PROBLEM
Any brake system problem has to be regarded as a major safety issue and your car should not be driven until the problem has been resolved by a mechanic.