Aact 425 [portable] Guide

Set your DMM to Ohms (Ω). Measure resistance between the two small terminals (the coil). A healthy AACT 425 should read between 10 and 30 ohms. An open circuit (OL) indicates a burnt coil. A short (0 ohms) means the coil is fried.

The may not be glamorous, but it is the silent gatekeeper of power in thousands of trucks, trailers, and industrial machines. Understanding its function, recognizing failure symptoms, and following proper installation procedures can save a fleet hundreds of dollars in unnecessary service calls and stranded vehicles. aact 425