GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Tail light question

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Old Sep 14, 2018 | 10:12 PM
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GL550
Tail light question

I’m pretty new with this truck I was curious if anyone knows what this light is...I’ve been trying to figure out what it is and I’m stumped. It doesn’t light up no matter which switch I turn on or what pedal I press down. Sorry for the huge picture. I used my iphone to upload it.

Last edited by PopoySD; Sep 14, 2018 at 10:14 PM. Reason: added some text.
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Old Sep 14, 2018 | 11:05 PM
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'10 CL550, '12 GL550
It’s your rear fog light. By design the left one only illuminates (unless your vehicle is right hand drive in which case only the right side). Provides extra visibility of your vehicle to following drivers during adverse weather.

its activated at second pull out notch of the headlight switch when headlights are on. Your front fogs will work with main rotator in Park light position, but rear only works when rotated to headlights. German logic that makes sense.

its very uncool to drive around with this on unless you are in severe weather conditions. In Germany you’ll be flashed if you do.

if your GL has HID lights and corresponding led daytime running lights, you do not have front fog lights. Given you have led taillights, it appears your vehicle is a later model that could be configured this way.

This is covered in owners manual of course.
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Old Sep 14, 2018 | 11:18 PM
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Thanks so much! I do have the LED drl's in front. After a couple of hours of reading up, I finally figured out they were the rear fog lamps. I just figured I'd ask here to see if I can get some answers while I look for it myself. So to set things straight, both left and right tail lights have the bulbs, but only the driver side lights up when switched on? Thanks much!
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Old Sep 14, 2018 | 11:35 PM
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That’s the German specification ... 2 rear fog lights would look exactly like brake lights and back in the days before leds they used exactly the same bulbs.
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Old Sep 14, 2018 | 11:50 PM
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Ok. Thanks so much! I appreciate your patience. I was wondering too if you have any idea, I tried replacing the front inner side marker bulbs with LED's. I bought "error free" led bulbs on Amazon, installed them and tried them out, everything worked fine at first. Then as soon as I started the engine and tried the turn signals again, the driver side sent an error code and wouldn't light up anymore, while the passenger side was still ok. I tried switching out the bulbs and it did the same thing (driver side out, passenger side works).
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Old Sep 16, 2018 | 01:22 PM
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I bought LED amber front turn signals. I would get a hyper flash only IF my daytime running lights were turned OFF. With the daytime running lights ON (led bar), no hyper flash and they no lights.
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Old Sep 16, 2018 | 02:20 PM
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ok cool, I'll try that. Thanks!
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