W124 ASR light comes on and car slows down...

[E280T]

Today while driving away from the house (w124 E280T, 1994, automatic) my ASR light came, not the warning light in the middle of the speedo but the one on the right side in the row of lights. From that moment on the engine didn't rev up anymore. This continued until I turned the engine off and back on again. Then everything was back to normal only to do the same thing again after about 3 mins of driving. Very annoying, but more important: Where should I look at first/what am I up against?

 

[television]

This is a hard one, not all that easy ASR faults as it could be the pedal or further back,,

I will find some info on it for you

 

[E280T]

Thanks Malcolm!
Perhaps there would be a way to just shut the system off cause the differential itself doesn't make any sounds, makes me figure it's the ASR unit rather than a mechanical problem(?)

 

[kth286]

You do not mean ASR you mean ASD which is the hydraulic control of the limited slip diff.

 

[jibcl500]

Is the battery ok???

jib

 

[grober]

What happened after the scenario you described? Did you drive the car back home or did you continue the journey? Did the problem go away or is it still there?

 

[E280T]

No I mean ASR cause that lights up in my dashboard and ASD is not on my car I suppose. Anyway, trust me, it's the ASR that's making drama. So this happened in the morning and after that I parked the car and left it till this evening. When I started it nothing went wrong. No ASR light burning up, not even after 3 minutes. And I drove it for about 20 minutes. Seemed to work fine. What was that?? Battery seems fine since it always starts without issues...

 

[grober]

One reason ABS or ASR lights up is low voltage. If voltage falls below a certain threshold then the system registers a fault condition and the warning light comes on. I suppose its possible you experienced a voltage "dip" for some reason. I think this is why jibcl500 asked about your battery. At this time of year cold morning starts do strain the battery and its interesting it happened first thing in the morning. An alternative/related scenario is you are experiencing an atypical voltage drop across the OVP relay which can happen if its connections are bad. This can lead to lot's of strange electrical behavior. Substitution is the best test for this. Other faults can be registered on the ASD/ASR system by faulty wheel sensors but this would be unlikely to effect the engine/throttle. The fact several systems were affected would indicate a systemwide type of problem like a supply voltage drop.

 

[E280T]

One reason ABS or ASR lights up is low voltage. If voltage falls below a certain threshold then the system registers a fault condition and the warning light comes on. I suppose its possible you experienced a voltage "dip" for some reason. I think this is why jibcl500 asked about your battery. At this time of year cold morning starts do strain the battery and its interesting it happened first thing in the morning. An alternative/related scenario is you are experiencing an atypical voltage drop across the OVP relay which can happen if its connections are bad. This can lead to lot's of strange electrical behavior. Substitution is the best test for this. Other faults can be registered on the ASD/ASR system by faulty wheel sensors but this would be unlikely to effect the engine/throttle. The fact several systems were affected would indicate a systemwide type of problem like a supply voltage drop.

Thanks for the reply. The battery could be the problem of course, but shouldn't it then stop once the car is running in stead of appearing again after 3-4mins? I take it that the car then runs on electricity that's received from the generator. I hope it is the battery but since the problem was limited to the ASR system and as a result causing limited throttle (not revving up higher than idle speed basically) I wonder if it's not the OVP relay that's either gone bad or is making bad connection. Where is this relay located? Another option would be the ASR control unit of course...

 

[television]

Putting it another way starting blips can happen,,when the voltage is too low some circuits cannot re set,,,cars that have ASR use the 9 pin version of the OVP relay, and yes the cars with ASR also have a special throttle assembly, and the car will lose power when it cuts in.

When the car has been run for 15 mins a re start should clear it if it is a low voltage thing, that is if the battery does have the full 12.5 volts.
If the battery has a short circuit cell they voltage may not get to 12V, but easily checked on a voltmeter.

There are three parts to it,,I do have info on the special throttle circuits if needed

 

[grober]

The OVP relay is located behind the flexible plastic shield behind the battery. It can be identified by the presence of 1 or 2 fuses on the top of it. Sometimes it just needs reseating in its socket but usually faults are due to the development of dry joints on the small circuit board inside. A cure is often effected by removing the cover and resoldering the component joints on the board. If this doesn't work then replacement is the only cure. As there are several versions of this relay as Malcolm says make sure you get the correct replacement based on the part no on the existing unit or your chassis number.

 

[television]

They only supply one now Graeme that is the 9 pin, with cars that use less they supply a plastic pin cover

 

[kth286]

No I mean ASR cause that lights up in my dashboard and ASD is not on my car I suppose. Anyway, trust me, it's the ASR that's making drama. So this happened in the morning and after that I parked the car and left it till this evening. When I started it nothing went wrong. No ASR light burning up, not even after 3 minutes. And I drove it for about 20 minutes. Seemed to work fine. What was that?? Battery seems fine since it always starts without issues...

There is only one ASR light and it is in the speedo.

The other light along the bottom you refer to is the ASD limited slip diff.

Why not post your full VIN up, it is in the windscreen for all to see.

We can then check the spec of your car.

ASR cars do not have a throttle cable, it is all electronic.

Does your car have a throttle cable or not ????????????

 

[E280T]

There is only one ASR light and it is in the speedo.

The other light along the bottom you refer to is the ASD limited slip diff.

Why not post your full VIN up, it is in the windscreen for all to see.

We can then check the spec of your car.

ASR cars do not have a throttle cable, it is all electronic.

Does your car have a throttle cable or not ????????????

I will post it later cause the car papers are in the car but it's a 1994 E280T Automatic. The light says ASR and not ASD. I live in Germany so maybe in the UK it's called ASD. But anyhow, just to make it clear. There is a light in the lower row and it burns red with the letters ASR.

 

[television]

It is OK I am clear that it is ASR as ASD does not limit the engine or have an electronic throttle

 

[E280T]

Okay Malcolm, but listen to this.
Today I checked it and the light that went on was orange (ASR), cause the red light was SRS. Either way, I drove again the whole evening with the car and it functioned just fine...

Could it be the battery after all? I sure hope so...

 

[E280T]

It was the red SRS light that came on and not the orange ASR light. Is there any way that the SRS system can block or reduce the throttle function?
My vehicle's VIN is WDB1240881F282204

 

[E280T]

It was the ASR orange light (sorry for the confusion) in the end. It came one once more but after that it left me alone...

 

[meanie]

Check for engine faults too, particularly throttle faults, because as Malcolm points out it also works through the electronic throttle.
You can probably rule out speed sensor faults as the ABS appears unaffected.
Possible fault in the ASR control unit.
Take an old phone charger socket & adapt it so that you can drive with your multi meter plugged into the cigarette lighter. That way you'll be able to get an instant overview of battery voltage when the fault crops up.

 

[television]

Yes there is no way that the SRS can affect the throttle, only ASR, as meanie really,, very hard systems to sort out