Asked in Mazda 323
What would cause the fuse to the tail lights and dash lights to blow on a 1993 Mazda 323 when the lights are turned on?
A couple possibilities: 1) the insulation from a wire is damaged and the wire is in contact with the frame of the vehicle. 2) A socket is damaged or the bulb is put in wrong or damaged. 3) if the vehicle has a trailer light plug, it could be wired wrong or damaged. 4) the light switch or relay (if it uses a relay) is faulty and must be replaced. Another 2 posibilities are, if a new stereo has been fitted the earth for the stereo may have been connected to the illumination wire which tests as an earth when the park lights are off. To test this just unplug the stereo, replace the fuse and turn on the lights. If it stops isolate illumination wire and connect steroe to a proper earth.
The other thing could be that illumination wire has been disconnected but not isolated properly and is shorting out behind radio.