Third Brake Light (CHMSL) Circuit Malfunction
What does B0060 mean?
The B0060 code means the vehicle's onboard diagnostic system has detected: Third Brake Light (CHMSL) Circuit Malfunction. This is a critical severity code.
Common Symptoms
- Center high-mounted stop lamp not working
- Third brake light does not illuminate with brake pedal
- Brake light warning on dashboard
- Only left and right brake lights function
- Failed vehicle safety inspection
Probable Causes (Ranked by Likelihood)
- Burned out CHMSL bulb or LED array failure Very High
- Corroded CHMSL socket or connector High
- Water leak into CHMSL housing Moderate
- Wiring break at rear window or trunk lid Low
Step-by-Step Diagnostic Procedure
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Inspect CHMSL bulb or LED assembly
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Check connector at CHMSL for corrosion
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Test voltage at CHMSL socket with brake pedal pressed
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Inspect for water damage in CHMSL housing
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Check wiring, especially at trunk or hatch hinges
Frequently Asked Questions
What does CHMSL stand for?
Center High-Mounted Stop Lamp. It is the third brake light mounted at the top of the rear window or on the trunk lid, required on all vehicles sold in the US since 1986.
Why does the wiring break at the trunk lid?
The wiring to the CHMSL runs through the trunk hinge area and flexes every time the trunk is opened and closed. Over time, this repeated bending can break the wires inside the insulation.
Can an LED CHMSL be repaired?
In most cases, LED CHMSL units are replaced as a complete assembly rather than repaired. Individual LED failures often require replacing the entire light bar or module.