Plug the charger into a DC power source. You should hear a clicking sound if the charger is working appropriately. If you don't hear a clicking sound, you'll need to check the fuses, which is explained in Step 3.
Plug the AC input into a known good plug. There should be a humming sound. If there's a humming sound the system is fine. If there is no humming sound, proceed to Step 6.
Disconnect the charger from both the AC and DC power sources if the charger doesn't click when plugged into the DC power source.
Remove the screws that hold the charger case together, using a Phillips screwdriver. Start with the handle screws and then do the front and back of the case. You can open the charger case by lifting up on the back of it and pulling it forward to release it.
Use a voltage meter to check the fuses of the DC cord and make sure there is continuity in the circuit. Set the meter to continuity and you should hear a beep when the testers are connected to the fuse. If you don't hear a beep, that means the fuse is bad and needs to be replaced.
Unplug the AC and DC power sources to check the AC cord if the charger isn't humming when plugged in.
Remove the charger cover, as explained in Step 4.
Use the volt meter to check the continuity of the AC cord. You would use the same procedure you used on the DC cord.