1. A computer-readable medium storing instructions that, when executed by a first computing system, cause the first computing system to perform functions comprising: receiving, from a second computing system, a message identifying a symptom of a first vehicle; and sending a repair tip to the second computing system, wherein the repair tip comprises: a first phrase describing a first procedure performed on a second vehicle that exhibited the symptom, wherein the first procedure performed on the second vehicle yielded a result insufficient to determine that a component of the second vehicle associated with the symptom is defective; and a second phrase describing a second procedure performed on a given vehicle, wherein the given vehicle is either (i) the second vehicle or (ii) a third vehicle that also exhibited the symptom, wherein the second procedure performed on the given vehicle yielded a result sufficient to determine that a component of the given vehicle associated with the symptom is defective, and wherein the component of the given vehicle is equivalent to the component of the second vehicle.