[W126 Coupe] Lights fixed for the moment

[Dick Spellman]

Cal,

The wire loom for the fogs runs down the driver's fender.  It's probably 
got a wear spot in the insulation that is shorting to ground.  I would 
replace this harness where it runs through the fuse box lower tray to 
one of the fuse holder screw terminal bases and on down to the fog 
lamps.  The grounds are right up front on the radiator chassis frame I 
believe.  I did not have the ability to operate my 83 sec fogs with just 
the parking lamps ON where the later year models do.  So, I built a 
non-MB circuit and wired this to the center wood dash using an MB cabin 
switch icon.  I also, added a low wattage indicator lamp and placed this 
in an open lamp slot on my instrument cluster so I'd know I was running 
with the fogs on.  The circuit is totally independent of the headlamp 
switch so no side markers just fogs.  Looks very clean and factory.  I 
run the euro city lights with or without fogs in this way when the side 
markers are on.    I did not document this alteration where it's not an 
MB factory item.

As for the early headlamp switch, I hope you don't have to replace it.  
It will be a fair amount of work if you do the solder at the switch.   
As I recall, under the switch rubber boot/cover you will find two rings 
of soldered terminals (one inner ring with small gauge wires and one 
outer with heavy gauge wires)  Harness repair on the switch presents 
tight quarters working vertical with a 25 watt iron.   It might be 
easier to do an in-line western union splice for each lead up the 
harness a ways if you feel the switch replacement is absolutely 
necessary.  Or as an alternative to messing with the switch, isolate the 
fog lead from the switch or at the base of it's fuse holder and isolate 
to eliminate the short to ground you describe.  Then build a new circuit 
as I did that is dependent on ignition acc voltage ON and in series with 
an early model  MB dome icon panel switch placed in the vertical dash wood.

Good luck.

Dick

  On 3/4/2011 12:29 PM, calvin young wrote:

> I apologize to everyone sending so many emails on the same subject 

> with the same info.  I think with the help of the list, the problem 

> has been isolated.  I disconnected the fog lamps and the voltages and 

> brightness were returned to normal on both headlights.  I am off to 

> have the car reinspected to get that reject sticker off the window.

>

> Whoever had the car before did some "custom" wiring and left a 

> problem. With your info Dick, I can either replace the switch with a 

> later model or do some rewiring to fix the fog lights correctly.

>

> Thanks everyone,

>

> Cal

>>

>> Cal,

>>

>> This may help as a further clarification re: US (NA) vs. Euro switch and

>> model year differences.  The early light switch is different than the

>> later models in that the harness is soldered directly to the switch

>> terminals in early model years.  The later model years employed a

>> plug/pin harness making switch replacement easy.

>>

>> The only added feature to either switch type was on the euro.  This had

>> a single +12VDC wire lead that was activated on the second pull of the

>> fog lamp function.  The first pull illuminated the front fogs on both

>> euro and NA models.  The second pull worked only on euro models and lit

>> the rear single fog lamp and lit up the center (orange) indicator lamp

>> on the switch handle.

>>

>> As for the ongoing dim light issue, why not disconnect the ground lead

>> temporarily at the lamp socket and hot wire a new ground to chassis to

>> see if this in fact gives the lamp full bright function?

>>

>> -\DIck

>>

>>>

>> ######################################################################

>> Men stumble over the truth from time to time, but most pick themselves

>> up and hurry off as if nothing happened.       --Sir Winston Churchill

>> ######################################################################

>>

> ThanksLou,

>

> I think that is exactly what happened here.  He wanted a brighter 

> lights for his driving situation.

>

>> Message: 3

>> Date: Fri, 4 Mar 2011 12:02:13 -0500

>> From: "millerlh at earthlink.net" <millerlh at earthlink.net>

>> Subject: Re: [W126 Coupe] dim passenger light

>> To: "dan at landiss.com, Mercedes Coupes Mailing Lists"

>> <mbcoupes at mbcoupes.com>

>> Message-ID: <380-2201135417213233 at earthlink.net>

>> Content-Type: text/plain; charset="us-ascii"

>>

>> I am no expert at all in these matters, but the previous owner of my 

>> 1990 560SEC had installed a new wiring configuration to support more 

>> powerful headlights before I got the car. I found this out when I 

>> went to replace a bulb and discovered the more powerful bulb he had 

>> installed.

>>

>> I would not have known the wiring had been changed, but was kind 

>> enough to respond to my inquiry as to why the bulb I found was more 

>> powerful than the Factory spec.. He told me he upgraded the wiring to 

>> avoid over powering the factory wiring (for want of a better 

>> description). Said he had wanted to avoid "outrunning the headlights"

>>

>> Is it possible that this may be one factor contributing to your problem?

>>

>> Lou Miller

>>

>> PS Don't ask me what he did or how he did it. He works on satellites 

>> and deals with that sort of stuff all the time. I just turn the key 

>> and enjoy.

>>

>>

>> That is also a sign of shaky grounds. the voltage at an "off" lamp 

>> should be zero, not over a half volt.

>>

>

>

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