3rd Brake Light Chevy Silverado: Complete Guide by Year (1999-2025)
Is your Chevy Silverado's third brake light not working? This comprehensive guide covers all Silverado generations, common problems, step-by-step troubleshooting, and when to get professional help.
Quick Answer: Why Is My Silverado 3rd Brake Light Not Working?
The most common cause (60% of cases) is a burned out bulb — a quick fix that takes 10 minutes. Other causes include blown fuses (15%), brake light switch failure (10%), and wiring issues (15%).
Contact Us
Bulb replacement (DIY)
Call for Quote
Professional service
10-30 min
Typical repair time
What is the 3rd Brake Light (CHMSL)?
The 3rd brake light, officially known as the Center High-Mount Stop Lamp (CHMSL), is the brake light mounted at the top-center of your vehicle's rear — typically on the cab roof or integrated into the rear spoiler on Chevy Silverado trucks.
Why the 3rd Brake Light Matters
- Federal requirement since 1986: All vehicles manufactured after September 1, 1985 must have a functioning CHMSL.
- Proven safety benefit: Studies by NHTSA show the 3rd brake light reduces rear-end collisions by 4.3% (about 200,000 crashes prevented annually in the U.S.).
- California law (CVC 24603): A non-functioning 3rd brake light can result in a fix-it ticket and fines.
- Eye-level visibility: Positioned higher than standard brake lights, it's more visible to following drivers, especially in traffic.
On Chevy Silverado trucks, the 3rd brake light also often incorporates a cargo lamp that illuminates the truck bed when you open the tailgate or activate it manually — making it a dual-purpose lighting system.
3rd Brake Light Specs by Silverado Generation
Each Silverado generation has different 3rd brake light designs, bulb types, and access methods. Find your truck below for specific information.
2019-2025
T1XX Body Style
Common Issues:
2014-2018
K2XX Body Style
Common Issues:
2007-2013
GMT900 Body Style
Common Issues:
1999-2006
GMT800 Body Style
Common Issues:
Note for 2019+ Silverado Owners
The T1XX body style (2019-2025) has an integrated spoiler assembly that makes 3rd brake light access more complex. Unlike earlier generations where you could simply remove two screws, the newer design may require removing interior trim panels or lowering part of the headliner. Many owners opt for professional installation on these trucks.
Common 3rd Brake Light Problems on Chevy Silverado
Based on our experience servicing Silverados in Sonoma County, here are the most common causes of 3rd brake light failures, ranked by frequency.
of cases
Burned Out Bulb
Symptoms:
- • Light doesn't illuminate when braking
- • Works intermittently
Solution:
Replace bulb (contact for pricing)
Urgency:
Low - DIY fixof cases
Blown Fuse
Symptoms:
- • Light suddenly stopped working
- • Other lights may also be out
Solution:
Check both fuse boxes (dash and under-hood)
Urgency:
Low - DIY fixof cases
Brake Light Switch Failure
Symptoms:
- • All brake lights not working
- • 3rd brake light works but rears don't (or vice versa)
Solution:
Replace brake light switch (contact for parts pricing)
Urgency:
Medium - Professional recommendedof cases
Water Intrusion/Corrosion
Symptoms:
- • Intermittent operation
- • Visible moisture in housing
- • Green corrosion on contacts
Solution:
Clean contacts, seal housing, or replace assembly
Urgency:
Medium - May need professional diagnosisof cases
Wiring/Connector Issues
Symptoms:
- • Flickering light
- • Works when wiggling wires
- • Intermittent operation
Solution:
Repair wiring, replace connector
Urgency:
Medium to High - Professional recommendedof cases
LED Compatibility Issues
Symptoms:
- • LED stays on constantly
- • LED doesn't work at all
- • Rapid flashing
Solution:
Use compatible LED or revert to incandescent
Urgency:
Low - DIY fix with right partsStep-by-Step Troubleshooting Guide
Follow these steps to diagnose why your Chevy Silverado's 3rd brake light isn't working. Most issues can be identified with basic tools.
Check the Bulb
Remove the 3rd brake light assembly and inspect the bulb. Look for a broken filament, blackened glass, or visible damage.
Inspect Both Fuse Boxes
Check the brake light fuse in both the dashboard fuse box AND the under-hood fuse box. The 3rd brake light may be on a different circuit than the rear brake lights.
Test for Power at the Socket
Use a multimeter or test light to check for 12V power at the socket when the brake pedal is pressed. Blue wire is typically brake signal, black is ground.
Check the Brake Light Switch
Located near the brake pedal, the brake light switch activates all brake lights. If no power at the socket, the switch may be faulty.
Inspect Wiring and Grounds
Check the wiring harness from the switch to the 3rd brake light for damage, pinched wires, or loose connections. Clean any corroded grounds.
When to Stop DIY Troubleshooting
If you've completed these steps and still can't identify the problem, or if you're not comfortable working with electrical systems, it's time to visit a professional. Electrical issues can be complex and attempting repairs without proper knowledge can cause additional damage.
Schedule Professional Diagnosis3rd Brake Light Replacement Cost Guide
Costs vary based on whether you DIY or use professional service, and whether you need just a bulb or the entire assembly. Here's what to expect in 2025.
| Repair Type | Parts | Labor | Total | Notes |
|---|---|---|---|---|
| Bulb Replacement (DIY) | Contact for pricing | $0 | Parts only | Easiest fix, 10-15 minutes |
| Bulb Replacement (Professional) | Included | Included | Call for quote | Quick service, same-day |
| Full Assembly Replacement (DIY) | Contact for pricing | $0 | Parts only | LED upgrades available |
| Full Assembly Replacement (Professional) | Included | Included | Call for quote | Includes diagnosis and testing |
| Brake Light Switch Replacement | Included | Included | Call for quote | If switch is the cause |
| Wiring Repair | Included | Included | Call for quote | Depends on damage extent |
LED Upgrade Benefits
- • Instant on/off (faster brake response for following drivers)
- • Lasts 25,000-50,000 hours vs. 1,000-2,000 for incandescent
- • Lower power consumption
- • Brighter output in daylight
OEM vs. Aftermarket
- • OEM: Exact fit, warranty (contact for pricing)
- • Quality aftermarket: Morimoto, Diode Dynamics (contact for pricing)
- • Budget aftermarket: Available (may have fitment issues)
- • We recommend OEM or quality aftermarket for best results
Professional 3rd Brake Light Service in Rohnert Park
Don't have time for DIY? Need expert diagnosis? Our ASE Certified technicians service all Chevy Silverado model years with same-day service available.
ASE Certified
Factory-trained technicians with Chevy Silverado expertise
Same-Day Service
Most brake light repairs completed within 1-2 hours
30+ Years Experience
Trusted by Sonoma County drivers since 1990
When to Choose Professional Service
We Recommend Professional Help If:
- • You have a 2019+ Silverado (complex access)
- • Multiple lights aren't working (electrical diagnosis needed)
- • LED stays on constantly (compatibility issues)
- • You've tried DIY and it didn't fix the problem
- • You don't have time or tools
- • You want it done right the first time
Our Service Includes:
- • Complete electrical system diagnosis
- • Fuse and relay testing
- • Brake light switch inspection
- • Wiring and ground check
- • Quality OEM or aftermarket parts
- • Road test verification
Rohnert Park Transmission & Auto Repair
6521 Commerce Blvd, Rohnert Park, CA 94928
Frequently Asked Questions
Common questions about Chevy Silverado 3rd brake lights answered by our ASE Certified technicians.
Is it illegal to drive without a 3rd brake light in California?
Yes. California Vehicle Code Section 24603 requires all vehicles manufactured after 1986 to have a functioning center high-mount stop lamp (CHMSL). Driving without one can result in a fix-it ticket and potential fines. More importantly, studies show the 3rd brake light reduces rear-end collisions by 4.3%.
What bulb does a Chevy Silverado 3rd brake light use?
Most Chevy Silverados (1999-2018) use a 921 or 912 incandescent bulb for the 3rd brake light. Newer 2019+ models may have factory LED units. Always check your owner's manual or the existing bulb for the correct replacement part number.
Can I put LED bulbs in my Silverado's 3rd brake light?
Yes, but with caution. Some GM vehicles have compatibility issues with LED bulbs in the CHMSL, causing them to stay on constantly or not work at all. If you experience issues, try a different LED brand designed for GM trucks, or revert to incandescent. Quality LEDs from Diode Dynamics or Morimoto typically work well.
Why does my 3rd brake light work but my rear brake lights don't?
The 3rd brake light and rear brake lights are often on different circuits with separate fuses. Check the fuse for the rear brake lights (usually in the under-hood fuse box). Also inspect the brake light switch, as some switches have separate contacts for different circuits. The turn signal/multifunction switch can also affect rear brake light operation.
How do I remove the 3rd brake light on a 2019+ Silverado?
On 2019+ T1XX Silverados, the 3rd brake light is integrated into the spoiler assembly. You'll need to access it from inside the cab by removing interior trim panels. Some models require lowering part of the headliner. Due to the complexity, many owners opt for professional installation on these newer trucks.
What fuse controls the 3rd brake light on a Chevy Silverado?
The 3rd brake light fuse location varies by year. On most Silverados, it's labeled "CHMSL" or "Stop Lamps" in the fuse box. Check both the interior fuse panel (driver's side dash) and the under-hood fuse box. Consult your owner's manual for the exact location and amperage (typically 10-15A).
How long does a 3rd brake light bulb last?
Standard incandescent 3rd brake light bulbs typically last 2-5 years or about 1,000-2,000 hours of use. LED bulbs can last 25,000-50,000 hours (essentially the life of the vehicle). If you're replacing bulbs frequently, check for voltage spikes or socket issues that may be causing premature failure.
Can a bad ground cause 3rd brake light problems?
Yes. A corroded or loose ground connection is a common cause of intermittent 3rd brake light operation. The ground is typically a black wire connected to the body near the light assembly. Clean any corrosion with a wire brush and apply dielectric grease to prevent future issues.
Related Chevy Silverado Guides
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