I just checked the bulb in my non-working 3rd Brake Light on my '97 E320.

The bulb is still good. I could probably have figured this out since I wasn't getting any Light Defective message. All other lights are working, brake or otherwise.

I'm not getting a voltage reading at the bulb socket or at the terminals that run to the socket when the pedal is depressed.

I checked the fuse box, all were good.

Question: is there an in-line fuse for this light? If so where would it be? Is there a brake switch that would only impact the 3rd Brake Light?

Anyone have any thoughts on what else could be causing this problem?

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'97 E320 Black Opal
'86 300E Smoke Silver / Burgundy (retired at 198K)
'63 Austin Healey 3000 Mk II (BJ7) (reluctantly retired)