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1987 420 SEL
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2,113 Posts
Discussion Starter · #1 ·
My lightout indicator has been on for almost 2 weeks now. Have checked and re-checked every light and none are blown. Where is the actual control unit located for the lightout indicator itself? Thanks.
 

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1988 560 SEC, '03 Ducati ST4s abs, '68 ZZ430 Camaro
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118 Posts
Have you recently changed any of the bulbs? I have leaned that my SEC is very sensitive to exactly what kind of bulbs are used. It may be as simple as using the original MB bulbs.
 

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1986 420SEL 2000 E320
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21 Posts
Bulb Out Warning

I recently had two episode of bulb out warnings so I can share some insights.

1. Eliminate some possibilities by using the headlight switch. If bulb out warning only comes on when headlights are on, burnt bulb is one of those used only at night - license plate, side markers, headlights, etc.

2. If warning light is lit regardless of headlight switch, it's most likely one of your brake lights. Have a second person help you by pressing the brake pedal so that you can see them while behind car.

3. Bulbs which are almost burnt but still lit will cause warning. That was the case for my side marker, located at the outermost slot in the tail light assembly's.

Good luck.
 

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Premium Member
1990 SEC
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4,289 Posts
Have you checked every light?
- 3rd brake light.
- each function for the corner/indicator lights.
- rear license plate illumination.
 

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1987 420 SEL
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2,113 Posts
Discussion Starter · #6 ·
I checked each and every light. Had a friend do the same. The light out indicator comes on as soon as I start the car. At first it would go out and come back on but now it stays on.
 

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‘83 380SL
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1,469 Posts
Have you checked every light?
- 3rd brake light.
- each function for the corner/indicator lights.
- rear license plate illumination.
one of the lenses for my license plate illumination things is cracked so it doesn't sit flush/tight so I have that annoying light on.. Time to take a trip to the junk yard..
 

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Premium Member
2012 CL550 4MATIC Coupe - RIP
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10,029 Posts
The Lamp Check relay is in the fuse block and it is Item "N7 EXTERIOR LAMP FAILURE MONITORING UNIT" It is Item F1 in the fuse block. The relay IS touchy and can fail. IF everything is good as you say, you can get one at a JY for under $10.00.
 

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2012 CL550 4MATIC Coupe - RIP
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10,029 Posts
I posted the Electrical Manual in the DIY section (Actually Ross put it there, but I scanned it.) and you can see all of the lighting circuits.
 

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Registered
1987 420 SEL
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2,113 Posts
Discussion Starter · #12 ·
Thanks all for your responses! Will keep you posted once this is sorted out. By the way, my baby has 228,325 on her now and still running strong. Almost time for PA inspection.
 

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2005 SLK350, 91 300SL with Pano Top, 04 S500, 2015 Tesla Model S
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2,173 Posts
I had the same problem and it drove me nuts. Integrity sensor lit and passenger side rear side marker would not light. I removed the sensor ( looks like a large relay box) and opened it up. Examined the circuit board and found a hairline crack. Heated it with a solder iron and Voila! all was well.
 

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1992 W126 500SEL (Euro spec with no cat) 104000 miles
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20 Posts
I had the same issue & spent a week or so constantly walking round the car to confirm that all the lights were actually working. As other members have said the car is very sensitive - my problem turned out to be a slightly faded rear parking lamp (a light I never use). Although the blub worked, it was a little dimmer than it's opposite number.
I changed the pair of them & voila, problem solved. Incidentally, I'd always recommend changing bulbs on this car in pairs.
 

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1987 420 SEL
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2,113 Posts
Discussion Starter · #17 ·
and, as an aside, make sure ALL bulb contacts are clean - go over them with emery paper, they truely are that sensitive...
You are the winner of the chime in to get problem solved contest!!!

It was my rear left side indicator light below the brake light. A very small bit of corrosion on the bulb end. At first, my mechanic was baffled cause he said "all the lights are working" just like I said. LOL!
 
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