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

LinkBack Thread Tools Display Modes
Old 01-13-2018, 01:29 PM
Innocent Bystander
Join Date: Oct 2016
Location: AZ
Posts: 100
Blowing Fuse

I fear this may be an unresolvable problem. The number 1 fuse blowing, which is the instrument lights, right parking lights. It will work fine for a day or two, even several hours of constant use, then seemingly without cause it will blow. Been through four already. Recent electrical work has been replacing the headlight switch, but that was months ago and this problem is only a couple weeks old. Ideas?

Also, perhaps related or not, a device I power through the cigarette lighter is immediately blowing its power supply fuse when i plug it in. There is nothing wrong with the device, it works fine in another vehicle. The lighter power is not on the number 1 fuse circuit, so it is powered when that fuse blows. Idea? Bad connection? Corrosion on contacts?
Reply With Quote
Old 01-13-2018, 01:37 PM
jake12tech's Avatar
Registered User
Join Date: Nov 2011
Location: Philadelphia, PA
Posts: 2,523
Check your grounds with a multimeter. There shouldn't be any voltage at the ground. Only at the power end. What you're describing indicative of a short.

Corrosion can add unwanted resistance as well. Make sure everything is clean.

also go on w124zone and find the ETM for some diagrams.
1999 E300 558K
1999 E300 213K
1998 E300 277K - GFs
1969 AMC AMX 80K
2009 Suzuki GSXR-600 27K
VW Golf 1.8T 5 Speed
Reply With Quote
Old 01-13-2018, 01:51 PM
Diseasel300's Avatar
Registered User
Join Date: May 2016
Location: Texas Hill Country
Posts: 3,999
Fuses blow because of excessive current draw. If it blows once, the problem should be found before replacing it. As you've found, the fuse will continue to blow. There's probably a chaffed wire somewhere that's touching something it shouldn't or rubbed through to the chassis and only pops the fuse when it touches.
'11 Honda Accord EX - "The Daily" 64K
'83 500SL Euro - "The Money Pit" 116K
'86 300SDL - "The Diseasel" 186K
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Reply With Quote
Old 01-13-2018, 02:22 PM
sixto's Avatar
smoke gets in your eyes
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,327
To the extent it’s safe to do, run without with front right parking light bulb, then without the rear right parking light bulb, then without gauge bulbs (remove the dimmer) until you find what blows the fuse. Check a wiring diagram for unlisted devices in that circuit (e.g., license plate lights).

98 E320s sedan and wagon
Reply With Quote
Old 01-13-2018, 03:12 PM
Registered User
Join Date: Dec 2006
Posts: 2,841
Removing the bulb doesn’t help if the problem is a chafed wire. Sometimes with this sort of problem, there’s nothing for it but to trace the physical cable run, and eyeball it for damage.
Reply With Quote
Old 01-13-2018, 03:15 PM
Diesel911's Avatar
Registered User
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 24,425
Don't know what vehicle you have. If the 82 in your member name indicates the vehicle year if the fuses you are using have plastic bodies they bodies melt or distort.

If that is the problem ceramic bodied fuses or the pointed buss type fuses.

What is the amperage of that device you were speaking of?

Perhaps you could run separate wires, inline fuse and separate socket for you
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
Old 01-13-2018, 06:21 PM
Registered User
Join Date: Sep 2001
Posts: 468
The appearance of a blown fuse can give a clue as to whether or it failed due to a direct short to ground or due to a slow build up of heat from a failing component like a blower fan or high resistance connection.

Look at the ends of the severed part of the fuse. Are the ends melted with a glob shape? If yes, there was a slow build up of heat from a component failing and drawing excess current or a bad connection in the circuit like a plug/connector that is loose.

If the severed ends are sharp/crisp it was a sudden high current draw probably due to a chafed wire as stated by previous members. Sometimes they are even sent in opposite directions.

It is common that the last repair is the problem, the headlight switch was replaced recently and is on that circuit. Can you swap it out with another one?

Good luck!!!
Does a Caddy stretch? No, but a Mercedes bendz.
Reply With Quote
Old 01-13-2018, 09:05 PM
BodhiBenz1987's Avatar
Registered User
Join Date: Dec 2004
Location: East Coast
Posts: 3,000
If my memory serves me, when I had a similar issue it turned out to be wear in the wires that run from the cabin into the driver's side of the trunk and end up at the license plate lights ... they pass through the hinge and over time wear in that area. I'd have to double check a wiring diagram and look through some of my old photos but I know I had to do that repair and I'm pretty sure that was the issue it was resolving.
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--369,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--137,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--3,700 miles
1995 S320, black/parchment--32,000 miles (Dad's car)
Reply With Quote


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 08:44 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page