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Outstanding Contributor
R129 500 SL 1991
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1,247 Posts
It is about an inch square with a clear plastic top. there are two fuses in it that also can have an effect on the ABS/ASR...
If you’re talking about the relay in the engine module compartment, that’s the OVP.
Resistance can build up in the contacts, wreaking havoc with ASR/ABS operation.

MB sequence of diagnosis of ASR/ABS light on with engine in limp home is to check the throttle linkage first (as you quite rightly pointed out), and then the throttle potentiometer.

Insight into effect of OVP is here
 

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Outstanding Contributor
R129 500 SL 1991
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1,247 Posts
My apologies, a 1995 SL500 has a base module instead of OVP.
 

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Registered
1995 SL500-129
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140 Posts
If you’re talking about the relay in the engine module compartment, that’s the OVP.
Resistance can build up in the contacts, wreaking havoc with ASR/ABS operation.

MB sequence of diagnosis of ASR/ABS light on with engine in limp home is to check the throttle linkage first (as you quite rightly pointed out), and then the throttle potentiometer.

Insight into effect of OVP is here
Where do I find the OVPR? Let us understand each other, I am not a tech, just an owner that since purchasing this vehicle with 18K kilometers on it, I have never had my hand out of my pocket, not even the soft top works properly, with red switch blinking non stop. But for now, I just need to know where that relay is.
Thanks, Rob
 

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Outstanding Contributor
R129 500 SL 1991
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1,247 Posts
Hi Ozzie Rob, I realised as soon as I read ‘38 pin connector’ in your PM, I realised I had made a mistake. You have a base module instead of OVP. Sorry for providing confusing information relating to earlier 500SL. My bad. 😕

However the principles of the tests are the same and testing the voltage at the control module still applies, but the component locations and reference voltages are different to earlier 500SL.
The test values for your vehicle are in this link here

You will see the first test is to check the voltage supply to the control module. This can be done with the module removed, but be careful, it is unfused.
For the reference voltage tests, control module must be in place.

My hunch is your problem is related to low voltage supply to control module. You need at least 11 V supply to control module for it to work properly.

So from your PM I understand you have tried emery paper on the pins of the control module.
You could try to clean up the socket using small strip of emery and then electrical contact cleaner. Also with battery disconnected you could try to tease the socket terminals closer with a small flat bladed screwdriver very carefully.

There is also an informative YouTube video by Victor on diagnosing ASR problem on your model here
 

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Outstanding Contributor
R129 500 SL 1991
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1,247 Posts
2nd part of Victors YouTube video is here

Are the symptoms the same as yours?
 
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