adaptive damping system help!

[g300d]

Every so often the ADS warning light in the instrument cluster goes on, red LED on switch lights up, and the ride stiffens, especially the rear suspension. Hardly ever happens with a cold engine, but switch on the engine when the car is still in operating temp and its almost a given to light up. Then it goes out after a while or stays on for the whole trip.

Off to the local dealer then! Car was hooked up to the computer, no fault codes related to the ADS. The ADS warning light in the cluster wasn't on at the time. We hooked it up again, this time while the ADS warning light was on, and the diagnostic computer couldnt establish a connection with the ADS control unit.

So, whenever the ADS warning light is off, the diagnostic computer has no trouble connecting and reading the ADS system and no faults are ever found. ADS warning on - cant read ADS computer.

Inspected the suspension visually for system leaks. Car has new air cells, new hydraulic oil to the correct level, and was bled properly. The harness leads were disconected and re-connected and sprayed with contact cleaner for good measure. Battery voltage tested and normal.

Diagnosis is a faulty ADS ECU, but I'm not so sure since it's such an intermittent problem. I dont wanna replace a $$$ part and find the problem still there! Any suggestions? Anyone with any experience on this? Please help!

BTW, car is a 1997 E50 AMG. Thanks!!!

[pcmaher]

I had a similar problem with my 95 S600. The ADS caution light would come on as soon as the steering wheel was turned, but only when the car interior was warm. Turned out to be the Steering Angle Sensor. The good news is that your system is defaulting to firm when the caution light comes on. That at least means that the system is still functional in "soft" and "firm" modes. I'm not liking the fact that you can't pull a fault code. There is a way to manually check all the components in the system, but you need a special MB breakout box to do this. Or, if you're a crazy nut like me, you can make your own and test each component. There is a very good test procedure listed on Alldata. I attached a link to a page in my web site that covers ADS. You may find it useful...

http://v12uberalles.com/ADS.htm

[g300d]

Thanks for the info! You are so right, there's hardly any meaningful info on the ADS system online (well, at least none that I could find). I got all the info i know about ADS while watching the dealer mechanic reading the car with the STAR scan tool. Your page is the most comprehensive read on the system I've had so far!

Actually now the problem is worse, it seems the car is on sport/firm mode all the time, even with the warning light off. I asked them to check the damper valves front and rear, so they actuated them by computer. They worked fine then, and voltage on all four were identically normal. No codes at all...only problem we saw via the STAR computer was that every once in a while it could not communicate with the ADS ECU, and these are the times the ADS warning lights go on...

Am going to try to go over the system myself with the help of your link. Maybe start with getting it back to comfort/soft mode. Will post results. Thanks again for the great link!