why won't my truck crank over what can it be help please on 2002 Ford Expedition

I changed the starter n the alternator they were bad when I tested them I also change the solenoid on the firewall n I got a new battery that also went bad but it wont start it just clicks at the solenoid. was running fine it just shut down while driving. also i hooked up the scanner n it won't link to it. please help

by in Pomona, CA on April 15, 2012
1 answer 2 comments
ANSWER by on April 15, 2012
double ck all your battery and cable connections, sounds like you have a bad one. also ck grds
COMMENT by on April 16, 2012
done checked all connections n no luck does any one know what sound does it make when the its not reading the chip on the key ? my just just clicks at the solenoid on the firewall a loud tack tack tackbut it wont crank or anything else well lights and radio work fine please help thanks
COMMENT by on April 17, 2012
its not you key if your solenoid is clicking. you have a BAD connection,12v is not getting thru