When ever i try to read the computer with a scan tool it says it 's not reading any data and to make sure its plugged in right and all that good stuff. But when I use a paperclip it will flash the codes to me.

I would like to use the scan tool to check for problems so what should I check for. I know the scan tool works because we use it on different cars as well. I've already checked all my fuses under the dash. Could the ecm be bad and how could I check to see if its good . Any help woud be appreciated!!!!!