2008 JK Wrangler Third Brake Light
 

Please help. When I step on my brake pedal all my brake lights work. After a few seconds the third brake light flickers and then goes out. I have tried replacing the fuse and also plugged in a new brake light. No joy. Could there be a short in the wire or is there a problem with my brake light switch.

Possibly a loose wire or bad ground.

Does it behave the same with the engine running and with the engine off and the key out?

Yes. With or without the key in.

Double post, for some unknown reason.

With the engine off, and the key out of the ignition...

If the regular brake lights remain on when the 3rd brake light goes out, everything is fine up to and including the brake pedal switch. The regular brake lights sense power from the 3rd brake light circuit after the switch. (When the engine is running, the regular brake lights are triggered by this and two other sources.)

Since you tried another 3rd brake light, and it did the same thing, my guess is there is a bad connection, or a short, after the brake pedal switch.

Hold the brake pedal down while you probe the 3rd brake light wire for voltage, starting from the light.

If the power is good at the light after it goes out, check the ground wire and its connections.

Mine did this also. Sometimes it would just quit working bc it would blow the fuse under the hood.It wasn't until I installed lug led lights on my spare that I realized there was a loose connection inside the rear door. Under that plastic piece.now all my brake light turn on and off at the same time.

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Thx for the input. I will try to track it down starting at the light.