New battery, bat cable ends, new alternator. Car
starts when jumped but just clicks when shut off. I
switched the relay so it's not that. Starter and/or
Solenoid? Bat cable? 3.8L V6
Note the diagram for starter motor. For testing, you could unplug starter relay, use jumper wire between terminals 30 and 87. As you can see, terminal 30 is hot all the time and fuse protected. With the jumper, the starter motor should crank the engine. If you try that, make sure transmission is in park or neutral and the parking brake is set. Make sure vehicle can't move. You could have a voltage drop on some circuit causing a problem, so when you boost it, there is enough added to circuit that it works?