[W126 Coupe] Light Issues

[calvin young]

See my comments in the notes below.  the car failed inspection and I want to get this done. Otherwise, I would consider this an interesting problem;

Cal  


> Whoa!  OK, you're giving some additional information here.  Looks like someone has been "working" on this electrical system before... some lights working, some poorly and some not at all..... and on both sides.   " The voltage on the passenger side of the car are different than those on the driver's side. "  How can the voltage be "different"?  I have learned that things in life often do not follow the script.  

I have learned Adding a new ground to a light shouldn't cause the light to not work (unless now you have no ground at all).  Same comment.  I thought it very strange.  That is why I requested a wiring diagram.  Too bad the auto schematic does not give voltages as a regular electronic schematic would.  Something else is happening here.  Could be indeed that you need a complete new (european) light switch.  Just might need a new switch.


> -Bellamy

> 

> 

> You can send me any questions and I will try to answer them. The wire 

> colors should be abbreviated, next to each wire. The numbers are an 

> approximate millimeter diameter. NOW THAT IS INFO THAT EXPLAINS MUCH.  IN ELECTRONIC DIAGRAMS THEY WOULD BE VOLTAGES.  SOMETIMES YOU CAN KNOW TOO MUCH AND WIND UP WITH THE WRONG ANSWER AND NOT ASK THE RIGHT QUESTION.  "C" numbers are connectors.  IS THERE SOMETHING THAT SHOWS WHERE THESE CONNECTORS ARE ACTUALLY LOCATED?  PAGE 208 FOR EXAMPLE.  


FROM THE DIAGRAM I CAN ALSO SEE THAT THE YELLOW IS ALSO HOT FOR THE HIGH BEAMS, AND HAS A HIGHER AMPERAGE.  

IS THE RIGHT HAND BEADLIGHT THE PASSENGER SIDE?


> 

> Note that the right and left sides have separate fuses and separate 

> grounds. The ground wires are almost always brown (GOT THAT) on MBZ. If you 

> happened to ground a white wire (like you might in household circuits) 

> you blew a fuse.  I FIGURED THAT WHITE WAS HOT.  

> 

> The wiring diagram style used in auto manuals is a hybrid between 

> conventional electronic schematics and pictorial assembly drawings. It's 

> not too bad after you get used to it.

> ------------------------------

> 

> Message: 6

> Date: Mon, 28 Feb 2011 10:27:53 -0600

> From: Dan Landiss <dan at landiss.com>

> Subject: Re: [W126 Coupe] Thanks for the diagram

> To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>

> Message-ID: <4D6BCD09.4070601 at landiss.com>

> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

> 

> It would help to know WHICH voltages are different. In the US wiring 

> scheme, at least:

> 

> 1) Yellow/black (at the left headlight) and yellow (at the right 

> headlight) should both be near 12 VDC with the low beams on, zero if off.

> 

> 2) White/black (left) and white (right) should similarly be about 12 VDC 

> with the high beams on, zero if off.

> 

> 3) All brown wires should be near zero no matter what lights are on or off.


I AGREE WITH ALL OF THIS, BUT THIS IS NOT THE CASE.  I WILL CHECK MY INSTRUMENTS, AND REDO THE TESTS TO CONFIRM WHAT IS GOING ON.


> 

> None of the voltages are ever negative unless the black (negative) 

> voltmeter lead is attached to a reference that is not really grounded -- 

> and that could be the cause of the whole kerpuffle.  THIS JUST MIGHT BE THE CASE SINCE CONNECTING BROWN TO GROUND CUTS THE LIGHTS OUT.  AT A MINIMUM, I MIGHT HAVE TO RE RUN THIS GROUND WIRE.  

> 

> on 2/28/2011 10:04 AM Mister McGoo wrote:

>> Whoa!  OK, you're giving some additional information here.  Looks like 

>> someone has been "working" on this electrical system before... some 

>> lights working, some poorly and some not at all..... and on both 

>> sides.   "/The voltage on the passenger side of the car are different 

>> than those on the driver's side. " / How can the voltage be 

>> "different"?  Adding a new ground to a light shouldn't cause the light 

>> to not work (unless now you have no ground at all).  Something else is 

>> happening here.  Could be indeed that you need a complete new 

>> (european) light switch.

>> -Bellamy

>>

>>

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