Abstract: A short circuit detector for battery powered vehicle circuits has a current lead for connection to the positive battery terminal from which the battery cable has been disconnected, a sensor lead for connection to the disconnected cable, a silicon controlled rectifier and vehicle light bulbs connected across said leads for dissipating high currents caused by a major short, a trigger transistor connected across the leads for turning said rectifier on in response to the current drawn by any short as low as a few milliamperes, a minor short oscillator and a speaker for producing a constant frequency tone that signals a minor short, a major short oscillator for modulating said minor short oscillator causing it to produce a warbling tone that signals a major short, and a discriminator transistor responsive to the amount of current flowing across said leads, for energizing said major short oscillator only in the presence of a major short.