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Q: Really weird brake light activity

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Ok so I was working on a freinds car and she informs me that her brake lights don't work. So I got to inspecting it looking for the issue. Well her brake lights and running lights are the exact same bulb but with 2 coils. Both coils were in tact, there are no blown fuses and I figure the wiring is fine cause the running light coils still work in both lights. Now I know about the hole brake switch issue but here is the kicker, there is a third brake light on her tail fin and that one works like it should. So any suggestions

It is possible both bulbs are burned out. The higher wattage brake light filament in each bulb should be tested with an ohmmeter to make sure the filament is intact. The bulbs can also be powered off the car to see if both filaments work but be wary of short circuits if you try something like that. If the bulbs are good, check for corrosion and/or faulty connections in the bulb socket, wiring, and/or terminals. Finally, check for power at the bulb socket and check the circuit ground. If there is no battery voltage, obviously the circuit will have to be traced to find the fault. If there is voltage, check the ground. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a brake light bulb circuit diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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