Driver side rear brake/turn signal does not work?

LEDESMA94

MEMBER
2012 FORD F-150
3.7L
V6
2WD
AUTOMATIC
115,000 MILES

Hello, I recently came to notice that my brake light and turn signal do not work on the driver side in the rear, but the taillight does. For this truck, it uses two bulbs for all three functions. At night when I turn the light switch on, the taillight turns on, yet when I press the brake light, the two bulbs on the driver's side turn off. When I try to signal that I am turning left, it does not flash. I have changed the bulbs and checked the fuses, yet it didn’t fix the problem.

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,320 POSTS

Hi,

I looked through the wiring schematic and need you to check something. At the left rear light, you will find a gray wire with a brown tracer. That is the power supply for the signal and the brake light. Using a test light or multimeter, I need you to check if there is power to that wire.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

If there is no power, I need you to locate splice (S401) see pic 2 for location. I need you to check to make sure it isn't damaged, corroded, or simply disconnected.

I also suspected it could be a ground issue, but if that was the case, the parking light wouldn't work or the right side.

Do this and let me know the results.

Take care,

Joe

See pics below.

Images (Click to make bigger)