As a customer with an uncommon vehicle issue, you may find it is best not to speculate on the issue, and simply tell the technician "fix it". Any information you can provide the technician is helpful, and the technician will go into diagnosing an unknown issue, also known as general diagnostics.

When a vehicle comes in for repair, and there is an obvious fault, such as "the wheel bearing is grinding or the brakes squeal at stop lights", these problems are generally not diagnosed, as the technician already understands the problem after inspecting the vehicle. Problems such as, "I hear a thump sometimes" or "my car feels like I'm in an airplane", are more vague, and until the technician knows what system is at fault, or verifies the existence of a fault, the process used is general diagnostics. With general diagnostic procedures, the servicing will systematically move through the systems of a vehicle until the fault is uncovered.