What kind of a meter are you using? Some meters have a slow response, so the turn signal interval might not allow a full reading.
You should get more than 12V
at the charge line with the engine running. I get 13.4 V while running, and 12.6 with the engine off. My lights read 12.5V.
Do check your meter first - I own 4 of them and one of them is drastically off.( It's a digital one from Radio Shack)
Also, make sure that there is no corrosion where you put the ground connector, and that the terminals of the plug are corrosion free.
I am not sure what the brake wire should read - that one is not exactly the same on my vehicle as the lights, but yet the brakes work great.
I make it a habit to check all the ground connections first, that way you can be sure not to have grounding problems.
Good luck with your test.