In two consecutive days I lost the hi-beam in one of my headlights. Now both just turn off when I engage the hi-beams.

I just saw a blue flash and the light went out both times. One headlight is about six months old and the other is about three weeks old. I also have some odd electrical symptoms elsewhere in the car.

First, the lights will occasionally dim along with the interior lights as I drive for no apparent reason. The alternator is about eight months old.

Also when I start the car the wipers come on for some reason. They make about two cycles and turn off on their own. My stereo comes on intermittently and will then occasionally turn off when I hit the brakes. It sometimes comes right back on and other times it stays off.

I have checked the fuses and they are all still good. I haven't done an extensive electrical check and I hope to avoid doing one.

Is there some kind of headlight relay that could be out?

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1993 W124 300D
-297K on the clock as I type this.

Okay, so my current daily driver, Coda, 1986 300SDL, is having a similiar headlight issue, but DIFFERENT.

The driver's side headlight HI BEAM will sometimes work. Turn lights on, flip to hi, and it works. A couple of hours later, turn light on, flip to hi, and it does not work. Yesterday at lunch, I checked it and it worked.

Someone tell me that this is the BULB. Anyone? I hate tracking down gremlins that come and go.

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
Cluster Needles Paint
New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

You checked the fuses- visually? Have you changed all of the fuses? This was recomended on another MB list, as the fuses get old and develop cracks.

The bulb is definitely a strong candidate. Maybe swapping the bulbs would eliminate any uncertainty.

Oh, cool. I have a spare bulb.

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
Cluster Needles Paint
New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

The W123 has both high and low beam headlights? Which position on the switch is which?

Turn all the way to the right and I get headlights. Turn one click to the right, and I get parking lights on both sides but nothing else. Middle is off...one click left/two clicks left are one-sided parking lights each. Pulling towards me turns on fogs.

I knew there was a light on the dash for high beams but I figured it meant something else, because its never come on.

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1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER

The combo switch/stalk could be getting flaky also.

High beams are part of the combo switch mounted in the steering column.

Parking, Headlights and Fogs are controlled by the rotary switch in the dash.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I would consider the possibility of a poor ground connection. My right side high beam worked intermittently a couple of years ago. After a bit of checking, I regrounded it and all has been well since. Although most of my electrical experience pertains to buildings, I have seen some pretty unusual situations develop from poor neutral (similar to ground in a car) connections (and some of your symptoms sound pretty weird).

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John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln

I was thinking the same but I have checked all the grounds of which I am aware.

I know that the previous owner upgraded the glow plugs to the pencil type and as such the ground on the front-most glow-plug is left disconnected.

Another ground on the passenger side front fender was disconnected so I tried to rig it to the negative post of the battery but I couldn't get a good connection. That is where I am going to start first. I will also replace some fuses to see if that helps.

To the guy who didn't know about the car having high beams, just push the turn signal stalk forward.

What other grounds should I check?

Thanks

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1993 W124 300D
-297K on the clock as I type this.

None. Low and high beams share a common ground. If the low beams work, the problem isn't likely the ground circuit.

Before you go on a snipe hunt, why not determine if the lamp itself works or not?

Yes, I agree. Check the easy stuff first. (Exception: in this case, with both high beams out, I'd check the high beam relay early in the game - see #5, below.)

1. Bulbs and their sockets. Consider new bulbs whether the old one looks good or not. I had a bulb in which one end of the filament came loose inside the bulb. Sometimes it worked, sometimes it didn't. Make sure the contacts in the socket are clean. Rub them with a pencil eraser or very fine steel wool until you get a shiny clean surface.

2. Fuses. The copper kind is better than aluminum. Remove the fuses and replace with new or at least clean the ends with fine steel wool. Sometimes a fuse that looks good in the fusebox will fall apart when you get it out -- the metal can develop a hairline crack. Don't depend on ohmmeter readings alone.

3. Ground connections. The system has many at various points through the body of the car. Remove the screw, clean the contact surfaces, re-install.

4. Headlight switch. Make sure all of the wire connectors on the back are clean and secure.

5. Combination switch and high-beam relay. Sometimes the "light horn" (headlight flasher - pull the stalk towards you, should work at all times to flash high beams) will work while the high beam position (push stalk away from you, locks in position) will not. The high beam position in my '85 uses a relay that can fail or become corroded internally, affecting both high beams. I don't remember where the relay lives, alas.

6. Miscellaneous. Wires and connectors and such. Could be anywhere, miserable job to track down, that's why it's last.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Well, I suspect that since a three week old lamp went out one night and a six month old lamp went out the next night that something other than the lamp is to blame. The low-beams work fine but neither of the high-beams do.

__________________
1993 W124 300D
-297K on the clock as I type this.

Does your high beam indicator light (in the instrument cluster) illuminate when the high beams are selected?

With the key in "run" and the headlight switch off, will the high beams work in the momentary "flash" mode?

What does that tell you?

Where was this blue flash?

lamps possibly brought in from China and not quality merchandise, hence their short life.

Yes, the blue hi-beam indicator in the dash does come on when I push forward the stalk.

No, the hi-beams do not work when I use the "flash" mode but the blue hi-beam indicator in the dash does come on in "flash" mode.

The blue flash I saw was in the normal field of light created by the head lights. When I turned on the hi-beams I saw a blue flash coming from the left head light one night and the right head light on the next night. The flash, I assumed, was the bulb going out but I find it very odd that a three-week-old lamp and a six-month-old lamp went out in consecutive nights.

Because of that, I assumed that the other electrical bugs I have witnessed in the car may have something to do with the lamps failing. I thought that maybe some kind of surge caused the lamps to go out. I do have a spare voltage regulator that I will try and see if that helps with the dimming issues.

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1993 W124 300D
-297K on the clock as I type this.