I Had this problem to but I got it fixed it cost me $320 to find the problem.
Its was 2 relays on the passenger side under the dash and they would not turn off when you turned the car off which the ECU should turn off but wouldn't, so its some fault with the ECU we had to rewire the 2 relays so they were hooked up to ignition or ON on the key column I cant remember which.
but that should fix it for you