[W126 Coupe] Light Problem

[Mister McGoo]

Yes, I mean "marginal", as in not completing a circuit, a weak connection.  Simply replace the fuse, whether good or "marginal".  It takes 15 seconds and costs about 19¢.  
 
The dim light is more likely a poor connection to ground rather than the fuse.  If your mechanic has tried the known good H4 bulb and socket from the other headlight, and the result was the same, AND if the dimness occurs on both the high and low beam, then the fault almost certainly is the ground connection. 
 
-Bellamy
 

> From: stevetsg at msn.com

> Date: Sun, 20 Feb 2011 20:42:19 -0700

> To: mbcoupes at mbcoupes.com

> Subject: Re: [W126 Coupe] Light Problem

> 

> Belamy, 

> What is a maginal fuse?

> Ernie

> 

> Sent from my iPad

> 

> On Feb 19, 2011, at 12:13 PM, "calvin young" <calvinyoung at cox.net> wrote:

> 

> > Thanks Guys,

> > 

> > I did switch the bulbs and that did not correct the problem. The mechanic switched entire light assembly (driver light to passenger and vice versa) and that still not correct the problem. So, the first place to look is the ground wire. I checked, but will replace the fuse.

> > 

> > Second, this car is a euro and has the complicated light system that allows one to switch on the parking lights on either side of the car. Lots of places in Europe have narrow streets, so they have this unique system that allows you to switch on the parking and front turn signal lights independently of each other, depending on which side of the street you are parked on. This switch, being made in 83 just might have developed a problem. First, I will replace the ground and see what that does. I might just rewire the darn thing to have the light work like American lights since this particular feature is not needed.

> > 

> > I will keep you guys informed.

> > 

> > Cal

> > ----

> >> Cal,

> >> If the problem is not a maginal fuse, you have a poor ground from that light. -Bellamy

> >>> 

> >> First, check the fuse to make sure it's making proper contact.

> >> 

> >> Second, have you tried replacing the bulb?

> >> 

> >> Third, if the bulb is OK, you may want to get a multimeter and measure voltage at the connector at the back of the headlight. At the same time, check the connector (make and female sides) for signs of corrosion or other crud and clean with a wire brush if you find anything.

> >> 

> >> Fourth, check your battery terminals to make sure they are clear and not causing any issues with poor or intermittent contact. Measure your battery voltage with the car both running and off. Should be 12-13.5V ish.

> >> 

> >> Fifth, check your ground point behind and below the headlight (typically brown wires going to a single screw) to make sure that it's making proper contact and there is no corrosion there.

> >> 

> >> Let us know what you find. One of these solutions should identify the problem. If it doesn't, then you may have another issue like a voltage regulator or even an alternator not generating the proper output, but that's a more serious bridge to cross if everything else checks out OK.

> >> 

> >> Cheers,

> >> Gerry

> >> 

> >> Hi Cal,

> >> 

> >> Most likely a poor ground connection,

> >> 

> >> Carl Hansen

> > 

> > 

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> > 

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