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ASR problem R129 SL600

EDZ649

MB Enthusiast
Joined
Jan 25, 2009
Messages
4,012
Location
1066 Country
Car
W210 E55 AMG
Since I have owned the SL it has had a fault with the ASR system.

The symptoms are as follows;

Start the engine and all the warning lights go out as they should, after approx 3 minutes or so the ASR light comes on and won't go out again until the ignition is switched off.

Before the ASR light comes on there is a faint pump like noise emminating from the rear of the car. I can't pinpoint where exactly, but you can also feel it through the seat in the form of a mild vibration.

As soon as the ASR light comes on the noise stops. This happens every time without exception and always takes exactly the same time for the light to come on.

I have previously had the codes read and it was diagnosed to be a fault within the ABS unit. So I sourced what was know to be a good used unit and had it fitted this morning. Unfortunately the same problem is still present.

I read the codes again on STAR and it revealed the following fault;

Code 021 Pressure switch A7/3s1 Long Term Monitoring

A7/3 is the ABS unit itself, however I can find no reference to the pressure switch or it's location.

Is anyone able to tell me where the switch is located please? I'm wondering if it is inside the unit but I'm hoping it is not as that would mean the unit I bought was also faulty with the same fault and what would be the chances of that?

Any help greatly appreciated.

Leigh
 
From a quick search on WIS you have a faulty pump or there is a leak somewhere.

The switch is part of the hydraulic unit.
 
From a quick search on WIS you have a faulty pump or there is a leak somewhere.

The switch is part of the hydraulic unit.

Thanks Jay. I assume then that you cannot just replace the switch, i.e. it's not available as a stand alone part within the unit if it were dismantled?
 

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