When you turn the key or press the start button in your 2010 CTS and you get that single click, multiple clicks or simply nothing at all, you might have to call a professional. But before you do, perform some basic checks that might identify the problem as something simple you can address yourself.
Make sure that the transmission is in Park for an automatic, or in Neutral for a standard. Locate the battery in the trunk. With a voltage meter set to DC volts, place the positive lead on the positive battery terminal and the negative lead to the negative terminal. The battery should have 12.65 volts. Have an assistant attempt to crank the engine while you're reading the voltage. If the voltage falls below 9.6 volts, the battery is bad. Make sure that the battery cables are tightly connected to the battery and free from corrosion.
Next, locate the starter relay in the fuse box under the hood. There should be an audible click from the relay when you try to start your car. If not, try temporarily swapping it with another relay with the same number of prongs.
Jack up the front of the CTS and support it on jack stands. Locate the starter on the bottom, driver side of the engine. Place the positive lead of your meter on the terminal for the small starter wire -- not the large battery wire -- and the negative lead to a good engine ground. If there is battery voltage when your assistant attempts to start the car, replace the starter. If none of these work, you'll need to use a code scanner to check the computer for codes to isolate the problem.
Make sure that you have gas in the car. Locate the fuel pump fuse in the rear fuse panel. Place your negative meter lead to a good body ground and the other to the metal tab on the fuse. If there is voltage on both sides of the fuse, the fuse is good. If there is voltage on only one side, replace the fuse. If the fuse is fine, remove the gas cap and have your assistant turn the ignition on while you listen at the tank fill port. You should hear a buzzing from the fuel pump for a few seconds, indicating that it is turning on. If you don't hear anything, the pump may have failed.
Locate the PWRTRN relay in the fuse box under the hood. Switch it with a similar relay to see if the car starts. If it does, the relay is bad. If this does not solve the problem, you need to scan the computer for codes. There are many possible reasons for failure to start, such as a bad fuel module or crank sensor, that the computer will be able to identify.
