Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-07-2008, 11:08 PM
Registered User
 
Join Date: Dec 2008
Posts: 40
My headlights are wigging out....

So I bought the car, a 300D about 3 weeks ago and neither headlight was working, only the foglights worked. I replaced the headlights about a week ago and they worked. Tonight I turned on the lights and the headlights worked, but both foglights, which were working last night were dead. I get to work and start playing around with the switch by turning the lights and and off, and now only the driver side headlight works. Both high beams still wor. What is going on here? Any ideas?
Reply With Quote
  #2  
Old 12-07-2008, 11:11 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
I have been struggling with this as well.

Go over all your grounds to body and check your pins to headlight as well as blinkers.

Replace as many fuses as possible! while cleaning all!! the contact surfaces in the fusebox.

thats a start.
__________________

Reply With Quote
  #3  
Old 12-07-2008, 11:13 PM
Registered User
 
Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 3,950
Ditto the ground check but it sounds like the headlight switch is acting up, especially since only the lights are affected. You might be able to spray it with contact cleaner (disconn. the battery first) and get it to work. I believe the rotary switch is fairly pricey ~$100+
__________________
Sam

84 300SD 350K+ miles ( Blue Belle )
Reply With Quote
  #4  
Old 12-07-2008, 11:25 PM
Registered User
 
Join Date: Dec 2008
Posts: 40
Seems weird though because the headlights initially were definately broken. I tested the headlight at the connector and there was power. Would a faulty headlight switch cause headlights to burn out?
Reply With Quote
  #5  
Old 12-07-2008, 11:28 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
Quote:
Originally Posted by SD Blue View Post
Ditto the ground check but it sounds like the headlight switch is acting up, especially since only the lights are affected. You might be able to spray it with contact cleaner (disconn. the battery first) and get it to work. I believe the rotary switch is fairly pricey ~$100+

What happens inside the switch that causes the issues? Its a pretty simple switch, correct?
__________________

Reply With Quote
  #6  
Old 12-07-2008, 11:38 PM
Registered User
 
Join Date: Dec 2008
Posts: 40
How do I get the headlight switch out?
Reply With Quote
  #7  
Old 12-07-2008, 11:40 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
the knob pulls straight out then there is a nut behind it. Undo that, then I believe it pulls out from the back.
__________________

Reply With Quote
  #8  
Old 12-07-2008, 11:40 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
21 or 22mm i forget
__________________

Reply With Quote
  #9  
Old 12-08-2008, 06:11 AM
Registered User
 
Join Date: Dec 2008
Posts: 40
Does anyone have a schematic of which terminal on the main headlight switch powers which light?
Reply With Quote
  #10  
Old 12-08-2008, 09:47 AM
KarTek's Avatar
<- Ryuko of Kill La Kill
 
Join Date: Jun 2007
Location: Bahama/Eno Twp, NC
Posts: 3,248
Quote:
Originally Posted by Hartge330ci View Post
Seems weird though because the headlights initially were definately broken. I tested the headlight at the connector and there was power. Would a faulty headlight switch cause headlights to burn out?
Keep in mind that reading power on an open connector is meaningless for the most part. Test electrical circuits across the load.

You can do this with lights be having the lamp plugged in, then touching the probe to the terminal you wish to test.
Reply With Quote
  #11  
Old 12-08-2008, 10:48 AM
Registered User
 
Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 3,950
Quote:
Originally Posted by Hartge330ci View Post
Does anyone have a schematic of which terminal on the main headlight switch powers which light?
I believe the schematic for that particular car (depending on the year, which you didn't mention) is available in the Haynes manual.
__________________
Sam

84 300SD 350K+ miles ( Blue Belle )
Reply With Quote
  #12  
Old 12-08-2008, 05:08 PM
Registered User
 
Join Date: Dec 2008
Posts: 40
I tested it at the lights.
At this point only the driver side low beam and high beam work and only the passenger side high beam works. This is where I am also getting power on the meter. No power on the meter anywhere else. Now, I am assuming since both headlights are powered together at the headlight switch, the headlight switch cannot be the culprit, correct? I would assume the same holds true for the headlight fuse, correct? So where could my problem be. The passenger side low beam and both fogs actually died at the same time, not at seperate times as I thought earlier.
Reply With Quote
  #13  
Old 12-08-2008, 05:13 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
have you changed the Pass low beam/ fog fuse yet. All of those symptoms point to the same circuit, it will be something very simple. 8 times out of 11
__________________

Reply With Quote
  #14  
Old 12-08-2008, 05:26 PM
Registered User
 
Join Date: Dec 2008
Posts: 40
Are the fuses for each side seperate or is it all one fuse. I haven't changed fuses yet because I don't know where to buy those funky fuses.
Reply With Quote
  #15  
Old 12-08-2008, 05:31 PM
Registered Hack
 
Join Date: Mar 2008
Posts: 4,601
I have trouble finding good replacements as well. There is a fuse for each side. But my fogs went out along with one low beam (pass) and replacing a good looking fuse fixed it.

go fig
__________________

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 11:01 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page