Why Are There No Returns On Electrical and Electronic Parts?
Too many people have tried to take advantage of the system. Instead of using proper diagnostic procedures, some people (mostly do-it-yourselfers, but also some so-called professionals) resort to trial-and-error parts swapping when they don’t know how else to fix an electrical problem. When parts they have installed do not fix their problem, they want to return them and try something else.
Electrical/electronic parts are easily damaged by improper installation or testing. Because electronics are very sensitive to voltage overloads, it does not take much of a voltage spike to ruin a component.
Unplugging a wiring connector while the key is still on can create a momentary voltage surge of hundreds of volts. Crossing up the wrong wires or using the wrong test procedures can also damage sensitive electronics. You have no way of knowing whether or not the part has been used or damaged.
Because of such risks, many jobbers refuse to allow returns on any electronic components. This may seem unfair to some customers, but it protects the next customer who might get a bad part that had been returned.
Most jobbers will allow returns or exchanges on rebuilt starters and alternators if there is a problem with the unit.