johnkk

Getting occasional brake light warning. Center and passenger out. Driver side OK.

used broom handle to hit brake lights and all OK. Drive a bit and warning goes on. Stop and start engine, and warning stops and lights work. Then warning pops up again after driving.

Checked all bulbs for continuity(all OK) and cleaned contacts. Gave a shot of contact cleaner.

Was hoping all were out and brake light switch would remedy, but driver seems to work all the time.

Not sure of wiring harness routing. Does it go to driver side first and then to center and passenger side?

I assume warning is triggered by current drop when center and passenger fail.

Any hunches would be appreciated.

johnkk

Problem appears to have been caused by bad contacts in the passenger side socket. Cleaned and bent them slightly to make a firmer connection.

Center brake light is wired from the driver side brake light. Cleaned and reconnected the center light connector.

So far so good.

Bentley routing and connector descriptions were incomplete between brake light switch and brake lights.

lucio_liu

loose connection? that's rare.
bad blubs and switch are more common on a c5.

GTA_Driver

Ditto.

To the OP- if you haven't replaced bulbs, your brake light switch is the likely culprit.

johnkk

Because my driver side brake light was always working, I had ruled out the switch.

The passenger side bulb contacts were indented after 12 years, so I filed them smooth and just tightened up the socket contacts by pulling them up gently.

New passenger side bulb is next step if it fails again. but no problems over the weekend.