Mercedes Tech Talk Discuss general technical questions and issues about your Mercedes-Benz. Moderated by a certified MB Tech.
Sponsored by:
Sponsored by:

Okay You M-B Electrical Geniuses- A Good Question for You!

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 03-14-2008, 01:59 PM
  #1  
Newbie
Thread Starter
 
1badmofo's Avatar
 
Join Date: Mar 2008
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
SL500
Exclamation Okay You M-B Electrical Geniuses- A Good Question for You!

RE: Cause of M-B SL500 Control Module(s) short

SL500 was taken to a non-M-B brake repair. No elect. problems when it went in the shop.

When they were finished and returned car-- the control module for the Conv. Top/Hard top was bad and showed a fault a short, and a low beam control module was also shorted.

The shop acknowledged that the battery went dead (they stated was bad), and that they either tried jumping it, or ultimately removed it for charging.

A COINCIDENCE... or can damage be done to the electrical system by jumping the battery, or by shorting one of the wires?

Now the manager (for 27 of their stores) is investigating... and is asking all the local Mercedes experts if this can happen. The local dealership in Scottsdale has stated it cannot happen... that there are 3 different fuses protecting the system.... and that control modules go bad all the time!

My guy (factory trained) says that the electrical systems are very delicate and tempermental... and that any slight surge or variance or anomaly to the electrical can fry modules.

Maybe it was coincidental... but that possibility diminishes after their admission of electrical problems (battery being run down) as well as them jumping the battery and then pulling it out... which is more like a "smoking gun" admission.
Old 03-14-2008, 05:51 PM
  #2  
MBWorld Fanatic!
 
lkchris's Avatar
 
Join Date: Sep 2005
Location: Albuquerque
Posts: 6,075
Received 205 Likes on 182 Posts
'07 GL320CDI, '10 CL550
I was once showed a box by a Mercedes mechanic that he described as as R129 top control box destroyed by battery jumping. He said $5000.
Old 03-14-2008, 06:26 PM
  #3  
XJ9
Senior Member
 
XJ9's Avatar
 
Join Date: Nov 2007
Posts: 259
Likes: 0
Received 0 Likes on 0 Posts
C350
Originally Posted by 1badmofo
RE: Cause of M-B SL500 Control Module(s) short

SL500 was taken to a non-M-B brake repair. No elect. problems when it went in the shop.

When they were finished and returned car-- the control module for the Conv. Top/Hard top was bad and showed a fault a short, and a low beam control module was also shorted.

The shop acknowledged that the battery went dead (they stated was bad), and that they either tried jumping it, or ultimately removed it for charging.

A COINCIDENCE... or can damage be done to the electrical system by jumping the battery, or by shorting one of the wires?

Now the manager (for 27 of their stores) is investigating... and is asking all the local Mercedes experts if this can happen. The local dealership in Scottsdale has stated it cannot happen... that there are 3 different fuses protecting the system.... and that control modules go bad all the time!

My guy (factory trained) says that the electrical systems are very delicate and tempermental... and that any slight surge or variance or anomaly to the electrical can fry modules.

Maybe it was coincidental... but that possibility diminishes after their admission of electrical problems (battery being run down) as well as them jumping the battery and then pulling it out... which is more like a "smoking gun" admission.

maybe destroyed by *reversing* the polarity of the battery cables while jumping. That can and does destroy lots of modules.
Old 03-14-2008, 06:27 PM
  #4  
Senior Member
 
benz-tech's Avatar
 
Join Date: Aug 2004
Posts: 263
Likes: 0
Received 11 Likes on 4 Posts
BMW E30. I've turned to the dark side.
i too have seen this happen. each time there was no real explanation. we 'assumed' that whoever jumped/charged the battery may have accidentally hooked up the cables backwards. either way they seemed to follow a dead battery. I'm assuming also you have a r129 car. what year?
Old 03-22-2008, 12:27 AM
  #5  
Member
 
brakel8's Avatar
 
Join Date: Jun 2006
Location: USA
Posts: 87
Likes: 0
Received 0 Likes on 0 Posts
ML500 AMG pkg
Maybe the bad module caused the battery drain? I've seen after a straight forward battery replacement on 203's the rear SAM just takes a dump for no reason.

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


You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Okay You M-B Electrical Geniuses- A Good Question for You!



All times are GMT -4. The time now is 03:52 PM.