Suspension Warning Light 500SL ADS1

Looking for some help please, the car is a 1990 500sl with ADS the suspension warning light has come on. The car has a 16 pin diagnostic and on checking the ADS slot got a reading of 4 blinks, this says acceleration sensor? The only sensors I can see are the ones which also control the ABS and ASR . But in spite of the warning light everything is functioning, ADS fluid level ok, car raises and lowers and also stiffens as it should. The pump is working and I am baffled at this stage any suggestions as to possible causes would be most helpful.

 

You are right that code 4 is indeed acceleration sensor. They are a common problem with ads 1. The sensor is located on the drivers side front wheel hub. X1 plug and held on by a couple of alen bolts. Mb will order it from Germany as generally its not a stock item.
They are around £300plus vat

 

There are two acceleration sensors, one on the inner wing under the bonnet and one on the lower control arm. They are different and measure different ranges of acceleration, you need to be sure which is faulty before you spend any money.

Code 4 is the lower control arm sensor, and code 3 is the body sensor.

Have you had any recent work on the front suspension? brakes etc..? or hit a large pothole? This can kill an old tired sensor.

 

You should have x3 wires going to the sensor. 12v +, earth, and signal.
It is worth checking the power and earth supply with the ignition on to eliminate the wiring.

You can then do x2 tests to check the sensor. A static test which should see the signal wire providing around 4.5 volts. And a dynamic test which involves pushing down on the front of the vehicle. The signal voltage should change as the vehicle is pressed down

You will need to recognise the correct pins on the ads ecu first in order to eliminate the wiring. Maybe someone else would have them to hand

 

Right, took a bit of messing about, but the following link has wiring diagrams, connector pinouts, legend and diagnostics for ADS1

https://docs.google.com/folder/d/0B8o7Y002jTi1VEJwNmxmWDNiOWs/edit

 

Thanks guys that is a great help its sometimes easier when things break and stop things functioning these other faults are so difficult when everything seems to function as it should, its great to tap in to the experience and knowledge on this forum. It does of course beg the question about whether the sensor is that important as everything seems to work, I suppose I won't know till I replace it. And yes the car has just had track rod ends fitted so that fits your diagnostics. Will post the result for other people to refer to. Thanks again.

 

It means your car is locked into the 'firm' setting and will not lower itself automatically at speed.

If you can live with that, you can save yourself £300+

 

Thats good to know, on the basis that I feel nothing wrong the saving £300 sounds good and I never worked out a way of knowing that the car actually lowered itself anyway at speed. The only problem is that knowing something isn't working gets to me so will look at it again in the New Year now I know that it is not urgent. Once again thanks for the help.

 

It's worth having a good ring around the mb breakers. Although its hard to get ads parts it's not impossible

You never know your luck

 

Try Mercman in Hayle Cornwall, I think he might have one of those accelerometers, at least he did a few months back.

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