Q: Rear Brake light and turn signal not working on driver side

Lighting problems like this can seem very confusing, so it is best to start with the basics. Check for power and ground at the turn and brake light sockets. I suspect in your case you will have a good ground but you won’t have any power. If you discover there is a bad ground, this will be the simplest repair. The power side of these lamp circuit is from the BCM. (body control module) So if you don’t have power at the sockets, you will need to locate the BCM and check for power coming out of the BCM.

Before you do that, you will need to connect a scanner that can communicate with the BCM. Believe it or not, you could have a BCM code that is stopping your brake and turn signal lights from working. Most people don’t have access to a scanner that can access the BCM, so you will most likely need to book an appointment with us to do this. If there are no codes in the BCM, it is most likely the BCM that needs to be replaced. Before I went and replaced it, I would check all the power and grounds at the BCM.

BCM’s are common failure items on Fords, so it is likely the problem. But you will want to do due diligence and communicate with the BCM. I recommend the following inspection to help you out. Electrical components are not working

Be sure to send the technician a note about your exact issue so he or she can come best prepared for your repair.

Good luck!