Brake lights not lighting up at full brightness

[Gregadeth]

I noticed recently that although my brake lights work, most of the time they don't light up as bright as they should (see pic 1). They're about as bright as the tail lights when those are on. Sometimes after a few presses of the brake pedal, they'll light up fully bright (see pic 2), but then when I press it again, they light up dim. This seems to me like a connection issue somewhere, because it's intermittent. I replaced all the bulbs with LEDs a couple of years ago, and just noticed this issue recently. Has anyone had this same issue and could direct me where to check first?

VideoCapture_20180807-020607.jpgVideoCapture_20180807-020618.jpg

[DMC5180]

The exterior lighting is divided into left and right fused circuits. Since this appears equal on both sides, I Would look at the common points in the feed circuit. Brake light switch and connections too it. Would be my first place to look at. Tarnished internal contacts can cause funny things like that.


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[Ron]

The brake lights are all on fuse #18. Check/clean the connections there and the Black Bulkhead connector #41 (Green/Purple wire = Stop Lights). Here, #35 supplies ground for both boards.
StopLights.jpg

There are different version of how the switch itself is wired in the footwell. If the connections to it are ok, suspect the switch itself.

[DMC5180]

Not all cars used Fuse 18. Mine is empty no terminals. I’ve never figured out if the use of fuse 18 was only on early VINs that was later eliminated or vice versa.


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[Ron]

+1

If fuse #18 is not used, there will be a an inline fuse down by the switch.

fwiw, I have found a few of the inline fuses to be the cause of no brake lights (not intermittent) while not appearing to be blown.

[aipri]

Not sure if this is the same issue or not, but I had a problem recently where my brake lights would sometimes be dim or not turn on at all. It turned out to be the little switch under the brake pedal that gets depressed when you press the brake pedal, not sure the official name, but DMC sell them. I replaced it and the brake lights were back to normal.

[Gregadeth]

I took the advice to focus on the brake light switch. First I bypassed the switch by removing the two wires and connecting them with a fuse. This made the lights come on nice and bright. The connectors looked good as well, which left only the switch itself as the culprit. I made a mental note to order a new switch, but then I got an idea. I grabbed a small hammer and gave the switch a few light taps and guess what, it fixed it! It's been a few days now and I've tested the brakes countless times, and it's been 100%. Gotta love an easy fix. I'll continue keeping an eye on it, just to be on the safe side. I'd advise others to check their brake lights as well. Your lights may be turning on, but they may not be at their full brightness, which in turn becomes a safety issue.