Dim brake lights

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2007 Mazda CX-9
I have a 2007 CX-9 Grand Touring. I don't know how long this problem has been around because I don't see my brake lights all that often. I noticed a couple weeks ago that the brake lights on the CX-9 are incredibly dim. I was driving behind my CX-9 tonight and you can barely tell that the brakes are on even at night. Is this a common or even known problem? And if so, how can I fix it?

I would prefer to not bother with the dealership service department, but I will go there if I have to.

Thanks...
 
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CX9/2007
I don't have that problem. Best to try to check with a voltmeter whether has the full 12V is should have or try to replace one fo the lights. Maybe they have gone bad.
 
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2007 GT FWD, Bose/NAV
do you guys have some aftermarket accessories installed that might be grounding out the lights?
 
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2007 GT FWD, Bose/NAV
Is there anyway to turn it off or disconnect it just to check if that is not the issue? With time some things can corrode themselves or connections can become corroded. Just a thought, might not even be the issue, but better to start somewhere.
 
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2007 Mazda CX-9
I finally gave in and took the truck to the mechanic for diagnostics. They traced the problem to a faulty brake switch (Part #L23266490). They found that 12 volts was on the input side of the switch, but only 6.6 volts were on the output.
 
I finally gave in and took the truck to the mechanic for diagnostics. They traced the problem to a faulty brake switch (Part #L23266490). They found that 12 volts was on the input side of the switch, but only 6.6 volts were on the output.
I'm having the same "dim brake light" issue on my 2007 CX9 GT, and neither of the local dealers have the part in stock (or even agree on what the part is).
How did you replace it, and does anyone have a parts diagram for this.

Thanks
 
Quick follow up to the replacement brake light switch. It was the culprit in my case and the part # was the same as above (Part #L23266490). It is a light green electrical switch with a white plastic rod extending at one end and is located above the brake pedal. To remove turn the switch unit counter clock wise approximately a quarter of a turn and it will come loose. then unplug the wires from the top and replace with new unit. There is a panel above the pedal assembly that needs to be removed by removing two plastic center pull type rivets to get access to the switch. One additional note: the white plastic rod is is adjustable (by pulling it out or pushing it in) and needs to be at the proper length setting to make the brake light come on and off when the brake pedal is pressed, otherwise the lights will either not come on or will always stay on. It took me some trial and error to get this right. I probably could have compared the length of the old switch to set length on the new one but didn't think of it at the time.

#67-210 in the linked diagram.
http://www.jimellismazdaparts.com/s...ukey_driveline=0&ukey_trimlevel=0&modelYear=0
 
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2010 Mazda CX-9 Touring
Fellas, I had the same issue - bad brake switch. I have 2010 CX-9 Touring which is over 5 years old and around 35K miles. Initially, I noticed that the high mount 3rd brake light did not work. I bought a new light (around $150) and replaced it. Still the same. Then, I replaced the cord that connects the light to the wiring. Still no luck. Then, I noticed that the old light and cord actually worked but were emitting very dim light not only from the 3rd brake light but all brake lights for that matter. So I gave up since I can't work with voltmeter. A friend of mine measured and it was only less than 4 volts coming into the light which helped him figure out that it is the switch. The switch is around $30 and about an hour of work. Now all lights illuminate brightly.
 
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CX9
I want to thank everyone who has contributed to this thread. I pulled great value from your information. I have a 2012 CX9 and discovered (by another driver yelling at me on the Interstate that I had no brake lights - of which I was thankful for) that my brake lights were very dim. Because of the accurate detail of this thread I called the dealer and explained my dim brake light issue AND that I had found a forum where other CX9 owners had the same issue. I even gave them the part number! They had me come in and sure enough it was a faulty brake light switch. Unlike some folks on the thread who could tell via a voltmeter that their switches weren't getting enough voltage on either the input or output side, my voltage was reading fine on both sides. That made the dealer doubt my claim of the faulty switch, but when they troubleshot everything else and could not find another cause they replaced the brake light switch anyway and sure enough that fixed it! And the part number on my invoice was, yep you guessed it, L23266490!
 
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2012 Mazda CX-9 Touring AWD
... but when they troubleshot everything else and could not find another cause they replaced the brake light switch anyway and sure enough that fixed it!
Hopefully they didn't charge you labor for all the time they wasted troubleshooting when you walked in and told them what was wrong from the start.
 
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2010 CX-9 Grand Touring
Fixed it for free!

Thank you to all who posted above, you saved me a lot of time and aggravation. I was pretty sure going in to this that the third brake light was not bad/dead. From the comments provided I looked more closely and realized they were all dim and the third light could just be seen in the extreme dark. With this confirmation, I knew I was on the right track. I went right to the switch as described above and removed it without even checking with a voltmeter. I realized the switch could be opened, so I popped it open and used some contact cleaner on it. Once reinstalled, the brake lights all work and are brighter than ever! Done in 30 minutes.
 
Last edited:

mazdadude

ZOOOOOOOOOM ZOOOOOOOOOM
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'16.5 Mazda CX-5 Touring
Fixed it for free!

Thank you to all who posted above, you saved me a lot of time and aggravation. I was pretty sure going in to this that the third brake light was not bad/dead. From the comments provided I looked more closely and realized they were all dim and the third light could just be seen in the extreme dark. With this confirmation, I knew I was on the right track. I went right to the switch as described above and removed it without even checking with a voltmeter. I realized the switch could be opened, so I popped it open and used some contact cleaner on it. Once reinstalled, the brake lights all work and are brighter than ever! Done in 30 minutes.
Good to know that it can be disassembled and cleaned. I LOVE fixes like this!

Was it easy to pop open? Did you see any obvious crud before you used the contact cleaner?

Sometimes you can run the risk of breaking off a plastic tab that holds it all together. Or my favorite was always when you disassembled something facing in the wrong direction, and all the pieces, springs, balls, etc. fall out, creating both a treasure hunt, and a fun little puzzle... (cryhard)
 
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CX- 9
Saved the day!

This thread saved my day! I had the same problem - top center brake light went out first, then the other brake lights became very dim. I was able to fix it for the cost of some electrical contact cleaner.

Getting the unit out is easy, but opening it is a little tricky. And be careful of the parts inside - they are pretty loose, and felt like they could fall out if I turn the two halves upside down. My unit had some good buildup of something in there around the contacts. I took the contact cleaner, wet the ends of of a few qtips, and polished it up. I also hit up anything metal I could easily clean up for good measure.

Here are some pics of the part. First, the green switch located above the brake:



The the switch itself opened. I highlighted what looked like the contact areas:


Lastly, I experienced the same thing as Aron in Toronto with regards to the plastic rod that protrudes from the unit. If you push on it or pull on it with any amount of force, it will lengthen or shorten. Well, suffice it to say that I inadvertently adjusted it when removing and prying apart the switch. After I first reinstalled the switch, the brake lights didn't work at all. Then I took it out, shortened the rod, tried again, and viola! bright brake lights!
 

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Mazda CX9
This was very helpful. I was having the same issue in my CX9. My fix was some what simple. After having trouble trying to get the green piece apart I remembered what you guys were saying about the white plunger. So I pushed it in two clicks and now the lights are all bright! So maybe theres no real need to do a disassembly of that part. Only need to make an adjustment.
 
G'day from Sydney. I had exactly the same issue today and came across this thread. It saved me lots of money and hassles. My mechanic who did a regular servicing today was unable to repair and told me that I might need to replace a relay or circuit which will cost minimum hundreds of dollars.
I just signed up to say thanks and add little information with regard to the white rod mentioned above. The green piece was a bit hard to disassemble as you need to pry up both sides at the same time. Also, the click-push type holder is quite fragile. I cleaned inside with contact cleaner spray. Mine had some build-up inside. After assembly, brake light remained on regardless of the brake pedal, then I remembered the white thing. Mine was too short to reach the pedal so it remained on. I needed to extend it but the white rod did not extend even though I applied quite substantial force. It could be only me but I had to pull up the white lever (not the white rod) with a pin near the connecter while shortening or extending the rod. Please see the photo. I hope this helps someone in the future.
 

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