This Manuf. Marketing Corp. Tow Doctor is a comprehensive trailer wiring diagnostic tool. It quickly checks 4-way, 6-way, and 7-way trailer wiring systems, identifying issues with ground, tail lights, turn signals, backup lights, electric brakes, and auxiliary power.

The unit is in excellent used condition, showing minimal signs of wear. All indicators are fully functional, making it a reliable tool for troubleshooting trailer light and brake connections. Essential for anyone regularly towing or maintaining trailers.