Step 7: Build Complete, Time to Test
1. Take a device that won't work if reverse voltage is applied. Cell-phone chargers are a good way to test the jack.
2. Turn the car on or just turn the key to the "ON" position.
3. Plug the device in. It should respond as it does to your normal power jack.
4. If it doesn't, reverse your NEGATIVE/POSITIVE wires either up in the dash or right at the jack.
5. If it still doesn't work, first check the fuse, then check to make sure your ground wire is making good contact with vehicle metal. If it isn't, try another screw.
6. If you have completed those steps and it still doesn't work, than PM me.