[Silver Benz]

Interesting. System is goofy...I can't wait for the day you find out the quirk with yours. Aside from all of your posts and a handful of others on this site, there is just no information on this system out there. It's like the great unknown, maybe the few of us are the lucky ones that get to start the trend with our issues and research for others years from now.

Chris

 

[johnathan1]

I realize that this is an OLDER thread, but I do in fact have relevant information to add!

It's unfortunate that the OPnever came back to say what happened w/ his car, as I am 100% sure I am facing the same issue currently with a 1992 600SEL I am repairing at the moment. I have replaced the rear accumulators, rear struts, and Steering angle sensor (all NEW Genuine MB parts), and while there is NO ADS warning lamp on the cluster, the system is still stuck in FIRM. I can force it to go to Comfort in HHTWIN (STAR/SDS same thing), and it works just fine. I have also tried replacing the ADS computer (used) and it didn't help.

Another thing I want to add, is that I have watched the ADS actual value readings on SDS, and noticed that the system actually DOES energize the valves at engine startup, but only for an instant, and then goes RIGHT back to FIRM. Hopefully we can figure out this dumb, goofy problem!

 

[arklatexV12]

I realize that this is an OLDER thread, but I do in fact have relevant information to add!

It's unfortunate that the OPnever came back to say what happened w/ his car, as I am 100% sure I am facing the same issue currently with a 1992 600SEL I am repairing at the moment. I have replaced the rear accumulators, rear struts, and Steering angle sensor (all NEW Genuine MB parts), and while there is NO ADS warning lamp on the cluster, the system is still stuck in FIRM. I can force it to go to Comfort in HHTWIN (STAR/SDS same thing), and it works just fine. I have also tried replacing the ADS computer (used) and it didn't help.

Another thing I want to add, is that I have watched the ADS actual value readings on SDS, and noticed that the system actually DOES energize the valves at engine startup, but only for an instant, and then goes RIGHT back to FIRM. Hopefully we can figure out this dumb, goofy problem!

I'm still around. Let me deal with some work and I'll sit down and respond properly.

 

[arklatexV12]

I realize that this is an OLDER thread, but I do in fact have relevant information to add!

It's unfortunate that the OPnever came back to say what happened w/ his car, as I am 100% sure I am facing the same issue currently with a 1992 600SEL I am repairing at the moment. I have replaced the rear accumulators, rear struts, and Steering angle sensor (all NEW Genuine MB parts), and while there is NO ADS warning lamp on the cluster, the system is still stuck in FIRM. I can force it to go to Comfort in HHTWIN (STAR/SDS same thing), and it works just fine. I have also tried replacing the ADS computer (used) and it didn't help.

Another thing I want to add, is that I have watched the ADS actual value readings on SDS, and noticed that the system actually DOES energize the valves at engine startup, but only for an instant, and then goes RIGHT back to FIRM. Hopefully we can figure out this dumb, goofy problem!

My honest feeling on ADS these days is that the manual adjustment within SDS to "comfort" is not representative of the standard (non-firm) driving mode, but of the absolute lowest firmness capability of the strut. ADS exists more to control body roll than it does to increase comfort. I have had seemingly perfectly-functioning ADS on three cars - my two W140s and my R129 - the latter of which was quite low mileage and excellent condition - and all exhibited this 'problem'. The biggest contributing factor towards ride comfort on the W140 is wheel size (OE 16" versus aftermarket or optional 'AMG' 18"+) and tire pressure, which should be 29psi, quite low by today's standards and not what your tire shop probably sets it as when they install your new tires.

 

[johnathan1]

Obviously I can't confirm this, but if that is the case, then under what circumstances exactly would the system set the valves to "full comfort"? I have a 1998 CL600 (ADS 2) and it always goes straight to comfort mode and STAYS there until the key is turned off. So, I don't think this "firm all the time" is normal behavior at all.

 

[arklatexV12]

Obviously I can't confirm this, but if that is the case, then under what circumstances exactly would the system set the valves to "full comfort"? I have a 1998 CL600 (ADS 2) and it always goes straight to comfort mode and STAYS there until the key is turned off. So, I don't think this "firm all the time" is normal behavior at all.

More accurately, I would use the phrase "minimum dampening stiffness", and as it adjusts stiffness in response to road conditions, the answer would be when it encounters a road obstacle that suddenly requires a lot of compression of the strut in relation to the others.

 

[johnathan1]

I have also worked on several other W140s with ADS, and they all behaved in the way I assume they should. With "full comfort" mode right after startup.

 

[johnathan1]

OK guys, I've got the answer: BAD BASE MODULE!

At least in my situation (1992 600SEL) the base module ended up having some kind of strange corrosion inside due to moisture coming in through the 4 fuse holders at the top. Replaced the BM with a good used one, and the ADS operates as expected. Good luck with your diagnosis!

 

[will_c140]

Having improper ride height and/or too much fluid/air in the system without proper (double) bleeding after any work (accumulators being one) can cause you to question what mode your car is in. It happened to me for 2 years. After getting the ride height corrected (via lever, and via re-bleeding the beer-keg of foam in my system), I experience clear difference when using damped mode vs comfort.