2003 QX4 brake lights problem

[qx4you]

I have a 2003 Infiniti QX4 with about 120K miles on it. Recently, I was pulled over for non-working brake lights. I thought it was strange since I changed them a couple of months ago.

I checked and the bulbs are not burned out. As I understand it, the bulb itself contains two filaments. One is for the tail light (low-intensity lamp) which is only on when the headlights are on. The second is for the brake light (high-intensity) which should turn on whenever the brake pedal is pressed.

The tail lights work when the headlights are on but when I pressed on the brakes, both of the brakes light are not working. The high-mount third brake lights does work when I press on the brakes.

I search a bit and read that this might be a grounding problem. Anybody know of this problem and know how to fix it?

Thanks.

[Towncivilian]

Welcome to NICO.

Since the center mounted brake light is working, the brake light switch or a fuse is most likely not the cause. Get a multimeter and check for voltage at the brake bulbs when someone is pressing on the brake to ensure the wiring is intact.

[Q451990]

to NICO!

If you have a plug for trailer light wiring, pay particular attention to it's wiring and how it interfaces into the factory wiring.

Good luck!

Heath

[nytrix]

Greetings to all... This is my 1st post here though the knowledge gained from reading this forum has been a real life-saver while troubleshooting the vast array of cryptic malfunctions my 2001 Pathfinder produces. Thank you very much for the help.

I'm having the same exact brake light issue as described in the OP.
Any ideas about the cause / cure before I break out the meter and waste another weekend afternoon on this PITA issue?

Thanks in advance!

[Towncivilian]

Welcome to NICO.

Does your third brake light alone illuminate, just not the two side ones? The easiest way to troubleshoot this is to swap in a known good bulb, and test for voltage at the bulb socket with the brake pedal held down.

[qx4you]

I just want to give an update. I took my car into my local mechanic and all he did to fix the problem was put in a new light bulbs. I was surprised since the first thing I did was buy new bulbs and tested it. It still didn't work at the time. I thought the old bulbs were still good by visual examination and plus the tail lights (low intensity) were still working.

It turned out to be a simple fix after all but I still couldn't explain why my replacement bulbs didn't work. Maybe I didn't insert them well enough. Anyways, I feel stupid but I should be more thorough next time.

Also, I just want to thank the moderators for keeping this forum up and running and helping out all the Nissan/Infiniti owners out there.

[Towncivilian]

That is odd indeed. Well, at least it was something simple! I'd be watching your brake bulbs to make sure they're still functional for the next week or so, just to make sure there isn't some other underlying issue.