Can a bad relay cause a fuse to blow - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 11-02-2011, 10:21 AM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Can a bad relay cause a fuse to blow

Just a thought here but i was thinking about it, could a bad relay for the secondary air pump cause a fuse to blow?
2004MBS430 is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 11-02-2011, 05:23 PM
BenzWorld Member
 
jnash's Avatar
 
Date registered: Apr 2005
Vehicle: 2003 S55 AMG
Location: Houston, Texas
Posts: 255
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
general answer

Typically relays draw a minimum amount of current to hold the contacts together while energized. I have never seen a relay coil short ciruit that would cause alot of current to flow and therefore blow a fuse. Most common failure with a relay is the actual contacts or less likely the energizing coil goes open circuit and no current flows to energize the contacts. If your suspect your particular relay is electronic rather than electro-machanical then its possible but unlikely as it too would more likely by design go open circuit.
See if there is an identical relay from another circuit in teh fuse box, try it, and then see if the fuse blows again. If it does its not the relay. Then put the supsect relay in the other location and test.

2003 S55
K&Ns, 80mm TB, NPI headers, X-pipe / 3in pipes, Kleemann Cams & 168mm Pulley, ECU & TCU tune. 550cc injectors, Meziere WP136S SC pump. ASP Idler Pulleys, 84mm SC pulley, SC belt wrap, Fuel rail loop, LFR7AIX plugs, NPI heat exchanger, -10C mod, shift paddles, TeleAid removed.
Lowering links (1.5" front, 1" rear), 18x9.5+35 offset rims, clear side markers, KG Key retrofit, H/W Valentine1, BT phone, BT AUX, laser jam, upgraded fans in seat backs, inline ABC mag filter.
jnash is offline  
#3 (permalink) Old 11-02-2011, 05:25 PM
BenzWorld Elite
 
Mercedes mechanic's Avatar
 
Date registered: Mar 2011
Vehicle: Timeship, see you yesterday, but you already knew that.
Location: 90210
Posts: 4,103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by 2004MBS430 View Post
Just a thought here but i was thinking about it, could a bad relay for the secondary air pump cause a fuse to blow?
Yes.
Mercedes mechanic is offline  
#4 (permalink) Old 11-02-2011, 05:54 PM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
thank you for your replies. I tested the relay and it was working so i ruled out a bad relay. I believe i found the culprit, the positive wire that goes to my secondary air pump had melted to the pump just short of the plug which i suspect was causing a short which was causing the fuse to blow in a protective measure for the pump. Your thoughts? i will have to wait till morning to determine if i found the problem because the secondary air pump only runs on cold starts
2004MBS430 is offline  
#5 (permalink) Old 11-02-2011, 06:00 PM
BenzWorld Elite
 
Mercedes mechanic's Avatar
 
Date registered: Mar 2011
Vehicle: Timeship, see you yesterday, but you already knew that.
Location: 90210
Posts: 4,103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by 2004MBS430 View Post
I believe i found the culprit, the positive wire that goes to my secondary air pump had melted to the pump just short of the plug which i suspect was causing a short which was causing the fuse to blow in a protective measure for the pump. Your thoughts?
Im not meaning to scare you. But you need to dis-assemble your K40, and inspect the circuit board. My bet is that the 40 amp (huge) fuse has loose/burned soldier connection's.



When the air pump draw's enough amp's it will burn the board but not pop the 40 amp.
Mercedes mechanic is offline  
#6 (permalink) Old 11-02-2011, 07:48 PM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
not to sound stupid but what is the k40?
2004MBS430 is offline  
#7 (permalink) Old 11-03-2011, 07:31 AM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Also where is the k40 located? Thank you, by the way i started it this morning and promptly blew another 40 amp fuse so i am learning toward what you said about the k40, i just need to find it
2004MBS430 is offline  
#8 (permalink) Old 11-03-2011, 08:04 AM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
where and what is the k 40?

First off thank you all for helping and getting me this far. I need some additional help locating the k 40 for my car any help or pictures you can provide are greatly appreciated.

Last edited by Skylaw; 11-03-2011 at 09:47 AM. Reason: merged with earlier thread to keep related matters together
2004MBS430 is offline  
#9 (permalink) Old 11-03-2011, 09:30 AM
Moderator
 
Skylaw's Avatar
 
Date registered: Oct 2004
Vehicle: 2005 S500 4-Matic, 1978 450SL "Christine"
Location: Tampa, Florida
Posts: 7,887
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 37 Post(s)
Lifetime Premium Member
There is a relay at position K in your right front fuse box. See http://www.benzworld.org/forums/w220...e-diagram.html

I don't know if Mercedes mechanic is referring to the board this relay is mounted on.

Permalinks 8 and 9 were merged with your earlier thread to keep responses from being scattered.

Warren

2005 S500 4-Matic
with Gateway 500 iPod integration

1978 450SL restoration project

Formerly: 2000 S500
with Ice>Link iPod integration
Moto V710 phone with MikBox
Upgraded Voice Control

Last edited by Skylaw; 11-03-2011 at 09:45 AM.
Skylaw is offline  
#10 (permalink) Old 11-03-2011, 09:47 AM
BenzWorld Member
 
Date registered: Nov 2009
Vehicle: 2004 S430
Location: Scottsdale, AZ
Posts: 75
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Hi Skylaw,

I have been chasing a CEL (p0410 i believe) which is a secondary air injection fault. I noticed that i kept blowing fuse f31 on cold start (went through 3 or them to confirm) and found that the positive wire coming off the plug to me Secondary air pump had melted partially (which i thought was causing a short and blowing the fuse). I wrapped the wire with electrical tape and replaced the fuse (f31) and it still blew the fuse this morning. Member "mercedes mechanic" suggested that i look into the k40 circuit board and see if anything had been burned out. I am also in the process of trying to bench test my secondary air pump to ensure that it is also working. I hope that this adds some perspective
2004MBS430 is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W220 S-Class

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Topic Author Forum Replies Last Post
c320 fuse #65 blow out help!!! fili209 W203 C-Class 4 11-06-2011 04:16 PM
Did I blow a fuse, or worse? MX-5.0 R/C107 SL/SLC Class 1 06-16-2011 11:17 PM
87 420sel fuse#5 starting to blow dstrybos W126 S,SE,SEC,SEL,SD,SDL Class 0 05-09-2011 01:38 PM
Repeated Fuse Blow on Fuse #7 mem W163 M-Class 2 03-16-2010 06:09 AM
Wiper Relay would blow fuse? jef_1_f R129 SL Class 3 05-21-2007 11:39 PM

Posting Rules  
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome