New battery, new alternator, new starter. When I turn the key it clicks and then nothing. The flashing theft light on dash continues flashing but nothing else electrical will work until I disconnect the battery and reconnect it. Help!
Double check the battery terminals and cables. Are they CLEAN and tight? Check the negative battery terminal as it is bad about breaking at the bolt when over tightened.
Check the grounds around the radiator core support. Are they clean?
Post the voltage at the battery. Attempt to crank and post the lowest voltage at the battery. Repeat measurements at the alternator main B+ terminal (the big one). A large difference in voltage means bad battery cables.
also check the battery terminal connectors that they haven't blown out, corroded, or melted. The ford factory connectors on my mustang literally blew out and it was held on by a little piece of the connector so i got some new heavy duty ones that won't blow, with the thin metal the connector is made of it could melt or corrode away.