Once you obtain the resistance value, Yahoo or Google "VATS key codes". You'll quickly find a listing of the GM pellet resistance/key chart, which will tell you which key (#1-15) you have.

Mary Barra, GM’s chief executive, has stepped up the company’s recall programme after a botched recall of cars with faulty ignition switches that were tied to 12 fatal accidents.

GM made headlines earlier this month when the firm called for the Federal government to mandate a higher sales mix of electric vehicles in the years ahead.