1996 Saturn. New Battery. Power in the cab for lights, beeps, dash, radio works fine. But nothing happens when I turn the key. Used a multi meter, battery showing full power. Multimeter on the fuses shows fine. Could it be the starter or solenoid or ECM? It was working fine 4 days ago. No sound when I turn the key.

 

Make sure your cable terminals have no corrosion on them. Also make sure the negative terminal end that grounds to the frame is clean and there is no corrosion between it and the frame.

Do you hear the fuel pump priming for about 3 seconds, and then ending with a definitive click when you turn the car to on but do not try to crank?

Try turning the key to crank while somebody watches the battery voltage at the same time. What does it read?

 

Start at the ignition switch and work your way through.