Analysis of returned fuel injector assemblies indicates a major portion have had internal electrical damage. Since the computer system will not allow enough current to damage the coil, it must be assumed that they are subjected to abnormal current loads during diagnosis.
Service Manual procedures state that all diagnostic testing of the injector be done using a test light. The test light serves as a 'current limiting' resistance which will protect the injector coil. If these procedures are not followed, the injector coil will be permanently damaged.
Full battery voltage applied across the injector assembly will destroy the coil in less than a half a second.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.