So I just purchased my wife a 2004 SL500 for a fun date night car etc...Car runs/drives great and everything works as it should except, the front suspension raises up while driving and won't return back down until the car is turned off. There is no ABC light, the car responds to the ride height button control when first started and sitting there. There is an ESP service warning, but I cannot get an actual diagnostic code that shows what the error is (using Snap On Solus and Modis with Mercedes expansion). When I did the suspension test and rodeo the vehicle responded correctly and checked out fine?

The car seems to do this every time it is driven. I believe it take a few minutes, or hitting a certain speed, but each time I stop and look while driving it is jacked up 3 or more inches in the front (looks like a 4wd truck). I am assuming ride level sensors in the front, but would they both go bad at the same time? The car doesn't seem to have any leak/sag issues. If I unplug the sensor on the top of the front struts, then the car stays at the normal height when driving, but of course displays an ABC fault warning. What should I be looking at? Thanks in advance for the help!

 

 

You should be looking at the input voltages the ABC controller is receiving from the four level sensors and the control currents it is outputting to the valves. I would use Star Diagnosis for that.

 

So I still have this issue occurring... I own an iCarsoft diagnostic tool now. The ESP light seems to be coming on due to the b24/15 lateral rate sensor. 2 questions in regards to that:

1. Where is this sensor located? I have searched and searched and can't find where it is located on an r230 chassis?
2. Could my car raising up the front suspension be related to that? I wouldn't think that is could, but please correct me if I am wrong.

 

http://benzbits.com/r230/YawRateSensor.pdf

And no, that has nothing to do with your ABC issues.

 

Rodney, thanks! I sure didn't think it could either. Do you think I have a fluid flush/block problem? It never drops in height only raises up in the front after you are driving. It almost looks like an old gasser hot rod

 

Refer to post #3 from Bobterry - does your iCarsoft tool read voltages from the level sensors?

 

The level sensor voltage is around between 2.4 and 2.8 volts on each corner when the vehicle is riding at the correct height. When the suspension raises in the front the voltage goes to around 1.25 volts on the front left and 3.1 volts on the front right. The rear sensor voltage seems to stay normal. What would cause such a voltage discrepancy on the front sensors and why do they raise the car up on both sides in the front even though the left sensor voltage goes lower and the right voltage goes higher?

 

I didn't notice before that you had done this. It's an excellent troubleshooting step. By unplugging a strut position sensor you disabled ABC and shutdown the control valves. Since that cured the vehicle rising, you eliminated the possibility of a leaking valve as the cause of your problem.

If I recall correctly, a lower voltage correlates with lower vehicle level; consequently, it seems to me the ABC controller is responding to an inaccurate signal from the left-front level sensor.

I'd focus on the left-front sensor, since it appears to be faulty. Have someone move the suspension while you watch the voltage response. Do the same at the other three wheels to have references for comparison.

 

This is a old post but had the same problem recently. My mechanic tried a bunch of stuff even a rodeo and found nothing. Eventually solved it by replacing all 3 accumulators. The two big ones were bad, full of fluid but the little one (between wheel and door) seemed ok, but fluid is hella expensive so why risk it. Surprisingly easy to do with basic tools. $500 or so for parts and fluid.

 

It is implausible for this to have corrected the problem. Chalk this up to some related task or coincidence.

 

It don't make sense that these things should be related.

 

I had a scary issue a year ago when my SL55 did a rodeo test while I was on the freeway going about 65 mph! I thought the big earthquake was finally hitting! This was only a few months after I had the entire ABC system replaced...shocks, pump, valve blocks and accumulators! WTF. Turns out it was the right and left front sensors on top of the shocks! (II forget which...lateral? Speed sensors?) STAR pinpointed the issue and was a cheap fix!

 

• OP, it sounds like you have at least two different problems, and need to work through the diagnostic faults.

First, check the battery voltage.

Second, check the connectors and wiring at each sensor.

Third, inspect the level sensor linkages very carefully.

Nick

 

Do you have it fixed? What was the cause?

Thanks,

 

So I finally have it fixed. There were two causes to this problem. First was because of both the front and rear control valve unit. I replaced the o-rings using the rebuild kits I bought from eBay ($50 each). It better the situation after rebuilding the valves, but the vehicle still raises up after a while of running, so I figured the pressure damping valve might be leaking too. There's no way to rebuild that unit, so just to replace it with a used one bought from eBay too (luckily I got a working unit). After all these, the vehicle works as it should be and is no longer sagging or raising on all four corners.

 

Is this the Pulsation Damper?

Thanks

 

Yes, the Pulsation Damper.

The problem was solved after I replaced the Pulsation Damper at the time. But now I can not be 100% sure that was the cause ( or at least the only cause to the problem), as now my car is still having the suspension height problem. The problem now is slightly difference from the previous. I can drive the car anywhere for any long with no problems. But after stopping, the car will still raise up itself, but very very slowly comparing to before. Plus, when it raised to the maximum height it would drop down to the base height itself too (before it would just stayed at the maximum height with the red ABC warning on dash). Also, a couple of months after I changed the things, my car's front end started to sag again. Now after parking it will totally sag down to the ground, but will pump up after I start the car, so no issues while driving.

I think by changing the front and rear control valves and the Pulsation Damper helped solved the previous problem but there may be other causes. In my case, I just didn't bother to dig down further as now I can drive the car normally. It just at parking or stucking at the traffic light for too long, the vehicle height will change.

Hope this helps!

 

Thank you kindly for the quick response.

I have a similar problem with my 2000 CL500.

First sign of trouble was the red 'Drive Carefully' message and fluid leaking from the front driver's side wheelwell. Turned out to be a ruptured hose -- Got that redone by a hydraulic shop and installed. Then immediately after a test drive I had to the front accumulator changed after the ABC reservoir overflowed.

After raising and lowering the suspension numerous times to bleed the system after those changes, when the car was shut off the entire right side would jump up and have the car leaning when in Park. So I got the rear accumulator changed, but still get the occasional red flash of 'Drive Carefully - Car Too Low' and the leaning problem still remains.
I've been trying to determine whether or not I need 1 valveblock or 2, front and/or rear, and have yet to get diagnostic codes done.

QUESTION: When you say you changed "front and rear control valves", do you mean the complete valve block assemblies, or just the control valves/solenoids which I believe are within the valve blocks?

Thanks.

 

I changed the whole valve blocks

 

Yes, it does help....Thank you kindly.

Now, maybe I can be of help to you.

The following is info I found in the MBZ Star Service - Service Manual Library Diagnosis DVD For Model 215/220.

Hopefully it will apply to the R230 as well.

There is a DTB (Daimler Technical Bulletin) from Dec. 05 outlining the problem of the ride height changing on it's own.....

Level changes occur intermittently and predominately after driving for extended periods. The vehicles level adjusts without obvious cause and usually quickly moves upwards or downwards and then rapidly corrects back to the specified level.

The Random Level Control is the result of contact issues on the printed circuit board of the body acceleration sensors (front left, front right and rear right-Model 215/220), in combination with the sensors heating up after an extended period of driving.

The contact issue can result in a higher internal resistance on the printed circuit board causing the sensor to output an incorrect signal, thus initiating an ABC adjustment.

Here's what you need to know...

Equipped with Code 487 (Active Body Control) RANDOM VEHICLE LEVEL
If the vehicle lowers randomly while driving or sporadically after stopping the vehicle, replace the body acceleration sensors with a manufacturing date greater than year 2002 wk. 01.

Note: Do not replace any other ABC suspension components.

Qty= 3; Part Name= Acceleration Sensor; Part Number= A004 542 35 18

Replace the two FRONT (left and right) Accel. Sensors for ABC and the REAR (right) Accel. Sensor for ABC.

Labour should be about 0.6 hrs for each of the two front sensors and 2.2 hrs labour for the right rear sensor. Call your dealer for parts pricing.

Also, try to apply 'significant' braking torque to the brake pedal when stopping the car as the ABC system is in Active mode when driving and the conditon you describe occurs when the sensors heat up on the circuit board after extended driving, then has "contact issues" if insufficient brake torque is not applied.
The random vehicle level condition will not occur when the ABC is in Passive mode, as the car only enters Passive mode a few seconds after the Tranny has been put into Park.

There are actually 4 Accel. Sensors on the car, but the 3 mentioned are known to have the problem "contact issues" on Model 215.

Good luck.