No brake light

Hello,

This sounds like you have got a problem with Ground 303, which is located on the left hand A pillar. In the diagrams down below I have included the backup and exterior lighting diagrams for your vehicle as well as the location of Ground 303 for you. Please inspect the ground and make sure that it is clean, tight, corrosion free, and making good metal to metal contact, and get back to us with what you find out.

Thanks,
Alex
2CarPros

Good evening,

You will need to test for power in and out of the brake light switch. From there, it goes to the turn signal switch and then to the bulbs.

You will need a test light or voltmeter to do the testing.

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

Roy

Thanks for the quick response. Anything on the reverse light not coming on? Seemed a few weeks ago everything was working just fine.

Back up circuit attached. Check the fuse listed for power on both sides.

Roy

Had someone come look at the lights. Used a volt meter and it said there was only 7.7 volts going to the taillights. I'm going to pick up a new brake light switch tomorrow and have him put it in for me. Still haven't looked at the reverse light though. One thing at a time.

Keep us updated.

Roy

Okay, not sure of this has anything remotely to do with my issue. The guy I had come to me just messaged me and mentioned he did some digging and said he thinks my issue could be caused by a combination switch for the turn signal. Those actually work, the brake lights don't work. Thinking I need to drop it off someplace more legit and see if they can dig into it. Thoughts?

Also my third brake light seems to be the only one working. forgot to mention that.

You need to test for voltage from the switch to the turn signal switch in the diagram that Alex and I posted.

If you have power to the switch, then yes, you have a bad multifunction switch.

Roy

The voltage was about 7.7 at the plug. This would keep the brake lights from working?

And when using my 4-ways all but one works.

7.7 where?

At the rear light...

No, you need to do the testing I asked you to do at the switch and at the multi-function switch.

Do those tests first.

Roy

Crap!!! That's right.

Keep me updated.

Roy

Okay, final update on my issue: Tail lamp harness needs replaced. The volts shot up to 12-13 at the plug under the bed. Then back down to 7-9 when plugged back in. Only thing is, Ford discontinued the harness and there's none new to be found. Having to check salvage yards for one, can't be guaranteed they can pull it off without damaging. And I can't find videos on removal/replace of the harness.

You need to be careful about removing it. When you remove it, you will know what needs to be done to replace it. It is not that hard, just time-consuming.

Roy

Thanks so much for your guidance, Roy. I'll keep this site in my favorites for the future.

You are welcome.

Always glad to help.

Feel free to leave a review for us. We appreciate all the feedback.

Roy

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https://www.sitejabber.com/reviews/2carpros.com

Did you respond? I got an email but nothing came through.

Roy

I asked a question about another topic.

It did not show here. What was the question? Did someone pick it up already?

Roy

It was unrelated to the light question so I had to submit another. Got a message from the admin.

Got it.

Let me know if I can help.

Roy

Well if you find the question, it was about my fuel system.

Already on it.

Roy

Okay, put a different tail light harness. It was used, but it is doing exactly the same as the original. 13 volts coming from power, after it's plugged in, there's maybe 8 volts. Trailer plus has 13 volts.

Okay, what about at the beginning of the harness? Do you have battery voltage?

Roy