Same thing as using paper clipe but gm use to make these .but you put it on the aldl top 2 on the right and turn key on but not running and you will get code 12 3 times telling you that you are on diagnostic mode then if you have any mal code it will stsrt flashing something like 2then 3 for like code 23 .it will do it 3 times then if you have any other mal code it will do it agsin