I have a clicking starter. new battery, good alternator, bench tested the starter seems good, I swapped the starter relay, it still clicks and the gear engages. One thing I just thought of is when I check the battery across terminals I get 12.31 V So I jumped the battery. No change just the starter gear engaging. Any help greatly appreciated.

 

Not knowing the complete history, are we sure the motor is able to turn over? Not seized?
After that , what is the condition of the battery cables?
Here is a simple test you might try.
Turn the headlights on and attempt to start the vehicle.
If the headlights go dim, could be battery,, defective starter or seized engine.
If the headlights stay the same brightness poor connection either to relay,or to starter or cable problem.

What you should consider is to leave the voltmeter connected to the two battery terminals , then attempt to start the engine.
If the meter drops below 9.5 volts you are looking for a new battery or the starter is shorted internally.
If the reading doesn't drop to near 9.5 volts you either have a defective starter or cable problem.

I listed 2 tests for you to try , You can try both or try whichever is easiest for you.. Let us know if you would like more assistance.