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-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 04-13-2022, 08:28 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
lamp failure monitoring unit

I am troubleshooting some lights that aren't working in my 90 300d.
All interior lights that are connected to the dimmer (probably the dimmer switch)
and the two front parking lights. I tested the voltage to the left side and I am getting 2 volts. The lamp failure light is on.
I just removed the lamp failure monitoring unit and I see that some of the metal strips are warped melted etc.
Also noticed a wire to the connector below has a little insulation missing-I might have just done this when I wiggled the connector off with a screwdriver. (I will fix this with electrical tape.
Should I replace with a used unit or do some closer inspection of the wires below? Most of the wires down there look pretty "new" without looking too closely.
Might the new used unit just burn up as well if there is an underlying issue...or would that just blow the fuse?

Reply With Quote
  #2  
Old 04-14-2022, 01:16 AM
Jeremy5848's Avatar
Registered Biodiesel User
 
Join Date: Mar 2006
Location: Sonoma Wine Country
Posts: 8,402
If the lamp failure unit has burned strips in it, you pretty much have to replace the unit. A good used one is probably the best choice. I had to do that with one of my cars some years ago.
__________________

"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
Reply With Quote
  #3  
Old 04-14-2022, 09:56 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
great, I'll look for one on eBay.
Reply With Quote
  #4  
Old 04-15-2022, 09:44 AM
JHZR2's Avatar
Registered User
 
Join Date: Jan 2002
Location: New Jersey
Posts: 5,265
Does the lamp failure feature stay on at all times, or just when you turn lights on?
__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
Reply With Quote
  #5  
Old 04-15-2022, 10:15 AM
Registered User
 
Join Date: Sep 2007
Location: Calgary Alberta Canada
Posts: 1,924
It stays on until the fault has been rectified.
__________________
92 e300d2.5t
01 e320
05 cdi
85 chev c10
Reply With Quote
  #6  
Old 04-15-2022, 12:03 PM
JHZR2's Avatar
Registered User
 
Join Date: Jan 2002
Location: New Jersey
Posts: 5,265
Quote:
Originally Posted by dieselbenz1 View Post
It stays on until the fault has been rectified.
The reason why I ask is because on my fairly pristine 91 300d, the warning light turns on for bulb check, but then only comes on when I turn on headlights, goes off when I turn headlights off. If it’s staying on all the time I have to wonder if something else is going on….
__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
Reply With Quote
  #7  
Old 04-15-2022, 04:23 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
With mine the light stays on only when the lights are on.
Reply With Quote
  #8  
Old 04-15-2022, 07:58 PM
JHZR2's Avatar
Registered User
 
Join Date: Jan 2002
Location: New Jersey
Posts: 5,265
Quote:
Originally Posted by jdulle View Post
With mine the light stays on only when the lights are on.
Ok that’s the same as mine.

Check the connections in the rear taillights. They seem to be the most prone to oxidation and corrosion, even if not exposed to moisture.
__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
Reply With Quote
  #9  
Old 04-15-2022, 09:32 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
There was a leak in the trunk lid which I mostly fixed, so it was humid back there for a while. I will have time to check all of that out soon.
Reply With Quote
  #10  
Old 04-15-2022, 09:32 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
strangely enough all of the lights in the back appear to work fine.
Reply With Quote
  #11  
Old 04-15-2022, 10:03 PM
JHZR2's Avatar
Registered User
 
Join Date: Jan 2002
Location: New Jersey
Posts: 5,265
Quote:
Originally Posted by jdulle View Post
strangely enough all of the lights in the back appear to work fine.
My understanding is that the contacts can be corroded and have just enough impedance to trip the sensor but still work.

My 240D doesn’t have the smarts, but the blinkers get that way sometimes. I’ll get fast blink even though both lights are illuminating; I guess one doesn’t quite take enough because of slightly dirty contacts. Moving the bulbs resolves it for another year or so.
__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
Reply With Quote
  #12  
Old 04-16-2022, 01:01 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
My plan is to go through the tail lamps and turn signals and clean all of the contacts and add some dielectric grease to it to protect it for a while.
Reply With Quote
  #13  
Old 04-16-2022, 01:02 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
I am also going to check the wiring from the relay to the sockets before I plug the new relay in.
Reply With Quote
  #14  
Old 04-16-2022, 05:02 PM
Registered User
 
Join Date: Sep 2007
Location: Calgary Alberta Canada
Posts: 1,924
Or it's the bulbs in the rear window a ton of people forget about.
__________________
92 e300d2.5t
01 e320
05 cdi
85 chev c10
Reply With Quote
  #15  
Old 04-16-2022, 08:29 PM
Registered User
 
Join Date: Dec 2021
Posts: 181
yes it looks like the 3rd brake light has been glued back together at some point so it might be a little harder to get into.

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 03:20 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page