16506-12V Heavy Duty Circuit Tester


Check on 6 and 12V systems. Use on accessories including lights, starters, alternators, cooling and heating components, radios and relays.


  • Spring supported strain relief.
  • Probe is insulated and super sharp.
  • Heavy duty ground clip and insulator.
  • Probe length: Approximately 180mm / 7"
  • Cord remains flexible in low temperatures.
  • Tough plastic handle lights up if circuit is good.
  • Coil cord design for easy use, wire stretches to 12-feet.
  • Specially designed long probe accesses hard to reach circuits.


VOLTAGE RANGE 6-12V                         
PROBE 180mm / 7"
COLI CORD 12-feet
  1. Check the bulb by clamping the alligator clip to the vehicle's negative (-) battery terminal and touching the test probe to the positive (+) battery terminal.  If the test light glows, the bulb is working.  If not, replace the bulb.
  2. Turn the power ON to the component that is to be checked. (The ignition may need to be in the ON or ACCESSORY position).
  3. Attach the alligator clip to a good ground (usually the vehicle's frame or at the point where the negative battery cable ends).
  4. Complete the test by touching the component with the probe or by piercing the insulation of the component's wiring.
  5. If the tester light does not glow, then either the circuit is faulty of power is not reaching the circuit.
  6. Repair any wiring insulation damage caused by piercing with electrical tape or silicone.