The International Border Electronic Crossing System (IBEX) incorporates low cost sensors on commercial vehicle braking systems to evaluate out-of-service conditions (OOS). OOS conditions include dragging, worn and inoperable brakes. Present roadside brake inspections require manual inspection under the vehicle to verify the operation and condition of the brake system components. To minimize these under-vehicle inspections, on-board sensors can monitor brake component conditions while the vehicle is in operation. Signal Processing Systems (SPS), Calspan Corporation, and Radlinski and Associates, Inc. (RAI) equipped three commercial vehicle tractors with brake shoe thermocouples and instrumented brake chambers. Brake condition data, acquired by the SPS “SmartLog” system, was recorded to a PCMCIA card and down-loaded on a weekly basis. Also recorded with the brake condition data was vehicle location at time of brake operation. This paper describes the design process resulting in the specification of the sensors installed on the tractors and includes examples of the data collected. The data validates automatic monitoring of brake OOS conditions with the IBEX system and demonstrates OOS information can be provided to the inspector without an under-vehicle visual inspection.