Disconnect ground cable from battery? - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 02-02-2009, 06:16 AM Thread Starter
Outstanding Contributor
 
keyhole's Avatar
 
Date registered: Sep 2006
Vehicle: 2004 CLK 240 Coupe
Location: Norfolk. UK
Posts: 10,450
Mentioned: 10 Post(s)
Quoted: 356 Post(s)
(Thread Starter)
Disconnect ground cable from battery?

The starting point in many service/repair procedures in the M-B WIS is to disconnect the battery ground cable. Now I can understand this is necessary on certain work, but it is listed, for example, when removing/installing ignition coils.

Can anyone explain what possible electrical damage you can do when doing this simple task?

(This is assuming that the ignition key is out of the car)
keyhole is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 02-02-2009, 06:31 AM
BenzWorld Elite
 
Date registered: Oct 2007
Vehicle: 2002 SLK 230 1986 560SL 2008 Honda CRV
Location: Rochester,NH USA
Posts: 3,664
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
IMO, better safe than sorry. Any kind of a spike will raise hell with these cars.
livefreeordie is offline  
post #3 of 12 (permalink) Old 02-02-2009, 06:39 AM
BenzWorld Elite
 
Diesel Benz's Avatar
 
Date registered: Dec 2005
Vehicle: 222.132 & 221.122 & 212.025 & 906.633
Location: Europe
Posts: 10,322
Mentioned: 3 Post(s)
Quoted: 34 Post(s)
I assume in case of ignition coils it is a safety/liability issue more than technical. The ignition system should tolerate pretty strong spikes anyway. Elsewhere it may be critical.
Diesel Benz is offline  
post #4 of 12 (permalink) Old 02-02-2009, 09:14 AM
BenzWorld Elite
 
Kajtek1's Avatar
 
Date registered: Dec 2005
Vehicle: W211 E320 Bluetec R129 SL500 - $1300 car ........ Ford F350 6l
Location: CA Bay Area
Posts: 31,751
Mentioned: 9 Post(s)
Quoted: 1119 Post(s)
Far going precaution, but so are ABS, airbags. ESP and tons of other gadgets we are using every day.
On my Ford pickup I welded frame for the dump bed. That was several hours of welding with high voltage spikes on the body. I never disconnected the dual batteries and nothing got fried. Ford has lot less electronics than MB, but still.
Kajtek1 is online now  
post #5 of 12 (permalink) Old 02-02-2009, 09:37 AM
BenzWorld Elite
 
Date registered: Oct 2007
Vehicle: 2002 SLK 230 1986 560SL 2008 Honda CRV
Location: Rochester,NH USA
Posts: 3,664
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
A couple of years ago i installed an anti-zap device on the battery which protects the electronics from spikes, it works great. Do a search for more info. Lots of post's about them.
livefreeordie is offline  
post #6 of 12 (permalink) Old 02-02-2009, 12:36 PM
~BANNED~
 
Date registered: Sep 2007
Vehicle: 99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
Location: FL
Posts: 4,583
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Why is this even an issue? It takes 30 seconds to disconnect the battery.
mr.xpowerseller is offline  
post #7 of 12 (permalink) Old 02-02-2009, 02:49 PM
BenzWorld Elite
 
Date registered: May 2005
Vehicle: '07 GL320CDI
Location: Albuquerque
Posts: 5,070
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
You're going to need a radio code following disconnecting the battery.

May have to "reset" windows, sunroof, etc.

Details in owners manual.

Kent Christensen
Albuquerque
'07 GL320CDI
lkchris is offline  
post #8 of 12 (permalink) Old 02-04-2009, 06:08 AM Thread Starter
Outstanding Contributor
 
keyhole's Avatar
 
Date registered: Sep 2006
Vehicle: 2004 CLK 240 Coupe
Location: Norfolk. UK
Posts: 10,450
Mentioned: 10 Post(s)
Quoted: 356 Post(s)
(Thread Starter)
What I am asking is - without the ignition key in place, and turned on, what exactly is live at +12v that could be shorted to ground? (Obviously excluding the clock, etc) Surely everything else is isolated via relays, control units, etc?

For the past 20 years I have changed light bulbs, and other electrical bits with no problems without isolating my battery. But not on M-B. so maybe just lucky.
keyhole is offline  
post #9 of 12 (permalink) Old 02-04-2009, 08:19 AM
BenzWorld Elite
 
Diesel Benz's Avatar
 
Date registered: Dec 2005
Vehicle: 222.132 & 221.122 & 212.025 & 906.633
Location: Europe
Posts: 10,322
Mentioned: 3 Post(s)
Quoted: 34 Post(s)
Quote:
Originally Posted by keyhole View Post
What I am asking is - without the ignition key in place, and turned on, what exactly is live at +12v that could be shorted to ground? (Obviously excluding the clock, etc) Surely everything else is isolated via relays, control units, etc?

For the past 20 years I have changed light bulbs, and other electrical bits with no problems without isolating my battery. But not on M-B. so maybe just lucky.
I did not check but the ignition system probably is out of power but most control units do have constant power on, many don't have switched power input at all. Those are just switched to low power mode via CAN signalling.
Diesel Benz is offline  
post #10 of 12 (permalink) Old 02-04-2009, 10:29 AM
BenzWorld Elite
 
Date registered: May 2005
Vehicle: '07 GL320CDI
Location: Albuquerque
Posts: 5,070
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
I frankly don't worry much about battery disconnecting.

The key is, of course, to be careful.

For DIY, it's your car, so you pay. Professionals need to be careful, as they shouldn't be able to charge for their mistakes.

I'd certainly never worry about this working on spark plugs, coils, etc. If these things retained charges, the engine would still be running. Certainly changed plugs/wires and CPS on an M112 with no worries.

Kent Christensen
Albuquerque
'07 GL320CDI
lkchris is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > General Mercedes-Benz

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:
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:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    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
    battery disconnect revolt1112 W163 M-Class 11 05-02-2012 11:39 PM
    how does one disconnect the battery? S320_on_18s W140 S-Class 13 05-21-2009 02:03 AM
    107 Battery ground cable corrosion nortonfan Vintage Mercedes-Benz 0 08-03-2006 11:04 AM
    hood cable disconnect kreuser914 W201 190-Class 3 02-15-2005 07:36 AM
    Battery Disconnect harb W210 E-Class 11 12-14-2004 01:36 AM

    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