[W126 Coupe] W129 500SL ASR problem

[Gerry Van Zandt]

Frank,

Your car is going into what is called "limp-home" mode.  Basically  
the computer is programmed, when certain faults trigger it, to revert  
to a basic map that allows you to drive the car, but you basically  
have to floor it, and you can go a maximum of about 40 mph when it's  
in limp-home mode.  It's for just what the name is -- to get you  
home, that's all.  Often as you found, stopping and re-starting the  
car will re-set it, at least for a little while.

Your mechanic is correct, as there are many things that can trigger  
an ASR light.  I wouldn't take the relays out however -- rather, I'd  
find the root of the problem rather than just going for an easy and  
incorrect fix that is not a fix at all.  Removing the relays is  
totally the wrong thing to do.

You need to bring your car into your shop (or using a homemade tester  
you can do this yourself - it costs $12 in Radio Shack parts to make)  
and pull the codes to see what is triggering that ASR light.  That  
will give you some indication as to the part or portion of the system  
that is triggering that code.  From there you can diagnose the issue.

The system on the 500SL is identical to that used on the 500E.  We  
have a wealth of related information on the BBS forum at www. 
500e.com.  There are dozens of posts and threads about this very  
situation, and what people have done about it, solved it, etc.

Cheers,
Gerry




On Sep 9, 2007, at 9:15 AM, mbcoupes-request at mbcoupes.com wrote:


> Message: 6

> Date: Sat, 8 Sep 2007 12:34:27 -0700 (Pacific Daylight Time)

> From: "Franco" <dusktilldawn at cox.net>

> Subject: [W126 Coupe] W129 500SL ASR problem

> To: <mbcoupes at mbcoupes.com>

> Message-ID: <46E2F943.000005.03688 at A-12BE4A5BDBA74>

> Content-Type: Text/Plain;  charset="iso-8859-1"

>

> Got a problem and need some help PLEASE

> Just bought a 1992 500SL and the ASR light comes on about once a  

> day and the

> car needs to be shout off and restarted in order to be driven  

> normally.

> I called my Benz shop and he told me it could be a lot of thinks  

> and an easy

> fix would be to just take out the relay's under the ABS cover....  

> We are in

> Arizona and I don't have to worry about snow or ice.... BUT are  

> there and

> long term effects by removing the relay's

>

> Sincerely, Frank

> 1987 560 SEC AMG

> 1989 300E

> 1992 500SL


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