Abstract: A battery jumper cable unit wherein the negative terminal clamps each carries a test probe circuit comprising a bar-ended test probe mounted in insulated relationship on the negative terminal clamp and electrically connected by an insulated test wire to the cable interconnecting the positive terminal clamps. A diode, resistor and lamp (or other attention-getting means) are interconnected in series in said insulated test wire and mounted on the negative terminal clamp. Additional attention-getting devices (different colored lamps, bells, speakers) may be incorporated if desired.