I found out an easy way to tell if you have a tail light out,,,,,,,(other than just looking)
I know that on my '04 Hyundai Sonata, the cruise control will not set if you have a burnt out tail light
FYI
It's becoming more and more popular to integrate some kind of sense on the tail lights. The down side to it, is if you ever hook up a trailer hitch, you have to install a power converter (or a pack of relays) to isolate the factory tail lights from the added draw of trailer lights.
I came across a Jeep Cherokee that had a display that would show if the taillights were malfunctioning. We had tried a diode converter but ended up having to add a power converter to keep it from telling us we screwed up the BCM/lamps.
my BMW has this for for turn signals, headlights (lo and high beams) as well as all the tail lights. I'm not sure how it's done but it has something to do with sensing how "good" the ground connection is, I guess. No ground = burnt out light bulb or no light bulb at all.
My wifes BMW has the same thing But It also gives false alarms sometimes due to moisture Replacing "O"rings solved this problem
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My wife thinks bagging a truck means you kick it in the truck nuts
If you wrap a number of turns of magnet wire around a magnetic reed switch, that should make the reed switch close when the brake light is on. I saw that suggested someplace, but haven't done it myself. This may not be feasible with LED brake lights, but maybe you just need more turns.
Then you could have the reed switch activate something, either to indicate that it's working, or warn that it isn't. A normally-close reed switch might be easier to work with, since it stays closed if there's a fault.
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Is this bass really strong enough?