We have a 2006 Ford Taurus that will not start. Battery is not dead, radio and lights work. Had it in, they created new keys and replaced the starter relay 2 weeks ago. Now car won't start again, even when jumped. What else could it be?
The Starter itself could be bad. The ignition Switch could be bad. The battery cables could be loose or corroded. If the car has a Fully charged battery and a correctly installed starter and you are getting one hard click and the dash lights/head lights do not go out when it clicks. Then the engine may be locked up and you will need to confirm it isn't by putting a socket on the end of the crank shaft and turning it. If there is a click , click , click (repeated clicks) then the battery is bad ( even if it is new) If you get a short click and the dash-lights/head lights go out when this happens, then your connections at the battery are loose/dirty/corroded or the battery cables are corroded internally or where the battery cables goto the ground and or starter are loose/dirty/corroded. These are the only options unless this is a ford then you may have a failed fender mounted solenoid. No Start Diagnostics