Cadillac Repair: second time, cadillac sedan deville, bump in the road

Question
I posted a question on friday jan. 28th and im am not sure it went through so lets try again.  I have a 96 cadillac sedan deville that won't start sometimes.  When I turn the key all the lights work and the radio but it wont start.  It doesnt even make a sound just a click.  If I open and close the door a few times and turn the key a few times it wil start right up.  it does not do this everyday.  The shop that I bought it from  put a new battery in and new terminals in and it still does it randomly.  In fact now that I have it back I hit a bump in the road any my check engine light came on for my emmisions.  My father is an mechanic but old school and usualy works on older model cars, he thinks their is a bad ground somewhere.  please help!!

Answer
Hi Barry, Hopefully you got the repost. After thinking about it alittle more I would test the PASSKEY system/ingition key and cylinder to make sure the reading doesn't go open when the key is turned. Then check for power to the ignition switch and leaving the switch. Just today I had a Grand Am that didn't have power comming out of the ignition switch and replaceing it got the starter working again. As for the check engine light you will need to read the code(s) to find out what the problem might be. Sometimes the computors have bad soldier joints that act up when bumped and when you take it down and with the engine running tap on the flat side with your finger tips if the light turns on get a new computor. If not hopefully the code will lead you in the right direction to repair the problem. Bill