When my headlights are turned on my brake lights do not work. The brake lights work during the day, but when the headlights are on and the brakes applied, the running lights, on both the left and right, go out.
You need to have your brake light bulbs checked for possible cross over connection inside the bulbs. The shorted bulb could do this. If all bulbs check out then the sockets need to be checked for making proper connections. If all this is ok then you have a switch issue and will need further diagnosis by a qualified mechanic. The most common problem is in the sockets or the bulbs.
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