Abstract: The method and apparatus includes the use of at least one pallet, an assembly line, a projector means, and an electrical testing means. Assembly of the wiring harnesses takes place on the pallets which are either independently powered or move on a powered conveyor line. In either alternative, the pallets move along a non-synchronous, power and free assembly line. An overhead projector means is provided above selected work stations to project instructions and diagrams on the pallet. Electrical testing means are used to test the wiring harnesses during assembly, prior to completion of assembly, and to control movement of the pallet to the next work station. The method includes testing partially assembled components for electrical opens, shorts and incorrectly assembled components on the pallet at intermediate stages of assembly and passing the partially assembled components to the next stage of assembly only when the components have been shown to be correctly assembled.