I can't remember for sure on an 03 and can't get to my manuals, but some of these vehicles have a temp sending unit for the gauge and a coolant temp sensor for the fans and so the computer can determine proper fuel mixture based on temp.
From what I remember, the relays get power from the underhood junction box. Have you checked for any blown fuses there? Also, I believe there are three relays and they run in a series for your system. Have you found 3 and been able to check if all don't have power?
Tuesday, September 9th, 2014 AT 6:24 PM