ABS problems on 08 Eclipse
 

I own a 2008 Mitsubishi Eclipse and my abs light won't turn off. I put a tester on it and it said I had problems with the abs sensor on the right side back of the car so I ordered that and changed it. Still to no avail. I also changed the entire unit behind the engine and STILL, the abs light won't turn off. I took it for a spin and braked hard a few times, I felt the abs not working and the brake light also appeared in the dashboard. I put the tester on it again and this time I had an error code for the back left wheel sensor. What can I do? Let me know, thanks.