Mercedes GLC Brake Light Issue Resolved

My 2015 Mercedes GLC diesel is acting up. The brake light failure warning keeps appearing, and the tail lights don't work when I brake. I scanned it and it shows a faulty brake light switch. I replaced the switch, but it didn't fix it. Could something else be wrong?

4 comment(s)

I had a similar issue with my GLC before. The error memory kept logging the brake light switch, even after replacement. Check if your floor mat is interfering with the brake pedal travel. The system is sensitive, and a slightly obstructed pedal can cause these errors.

A floor mat? I have thick mats in there for winter. I'll check. If the pedal wasn't fully returning, wouldn't that affect the braking too? I'm not experiencing any weird braking, just the brake light and error message.

The brake system is complex. Even a slight obstruction can trigger the sensor without noticeably affecting braking. The tolerances are tight. If the mat isn't the issue, get it professionally diagnosed. A short in the tail light wiring could mimic a faulty switch, but I suspect the mat.

You won't believe this. It WAS the floor mat! I removed it, and the brake light works now. The error message is gone. I feel like an idiot but also relieved. I owe you. Repair cost: 0€.

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