The glow plugs operate on a 7–volt system. The glow plugs DO NOT tolerate any over voltage. Full battery voltage will destroy the glow plug immediately. DO NOT test the glow plugs with a 12V source as damage will occur to the glow plug.Never bend, bump or knock the ceramic glow plugs.Ceramic glow plugs must not be handled loose in a container. Store, handle, and transport them only in original boxes.If there is any doubt about the proper condition of a glow plug, do not reuse it.Do not clean the glow plugs with abrasive or aggressive media.Avoid dipping the glow plug into fluids.Read Diagnostic Trouble Codes (DTCs). If a glow plug problem is indicated, do not start the engine.Disregarding these instructions may cause severe engine damage.Glow plugs are used to help start a cold or cool engine. The glow plugs will heat up and glow to heat the combustion chamber of each cylinder. An individual glow plug is used for each cylinder.