When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi, I'm looking at the ADS module in my 129.066 and all the schematics I have - both a single pdf of the ETM and the Star Classic DVD say this has a 41 pin connector.
Well mine aint! its 35. Both the above docs refer to schematic PE32.32-U-2000YA, Titled as of MY 1991.
Gutted all this docn has failed me in my hour of need!
So can anyone find a schematic that is correct for my car please?
Some data:
VIN WDB1290662F063286
Model 500 SL
Chassis 1290662F063286
Engine 119960 22 034910
Transmission 722353 03 727839
Order 0 2 839 50781
Approx. year 1992
Dealer Japan (839)
Interior leather light brown / java (274)
Options: 216
self-levelling suspension all-around, with adaptive damping system (ADS)
Background
- my ADS tends to error on steering column sensor and others, and thought I might just put a manual hard / soft control on the damping solenoids so I can get it off hard which it defaults to on error. At least until I get a chance to get it sorted. From my many years driving in it, the ADS didn't really kick in until fairly high speeds which I don't do much on our bumpy roads in this car. It's far less effective than the Airmatic in my W205 C-class. Plus I was always interested to know what it was doing so plan some LEDs to see if I'm right it doesn't do much at slow speeds.
Got the module out but guessing pin numbers makes my idea pretty untenable!!
Help appreciated!
Greg ADS1 pcb view ADS1 connector view
Oh well, a bit of measuring of R's between pins on the car socket randomly, found the solenoids! And it seems the schematic numbering works for the 35 pin plug.
Not sure if there never was a 41, and the schematic had it wrong, or it later changed to that.
Anyway, working on the next bit of the project now.
Thanks Andreas and MAH,
No, just the one big one and I think the pink one also perhaps - I'll check their value.
At this stage I'm getting codes for:
Front Solenoid valves1 that show up immediately on engine start after self diag I think.
Also steering angle sensor. And at one point wheel acceleration sensor, but that stayed clear.
My LEDS on the solenoids show the -ve pins are all at ground, and at startup, I get
briefly two flashes of the rear and left solenoids2 +ve drive, but not the right, nor the solenoid1 drive.
Then it errors and does no more.
Seems its testing and either finds no drive generated, or a short I suppose.
I measured fairly ok R's in finding the solenoids were there, so maybe its lost the output device drive. (or my monitor cct isnt quite right yet)
Anyway it has just got a bit troublesome to maintain, so figure I'll try a static drive next, to see if that does put current thru and the voltages / leds show ok.
If that gets me manual control of the stiffness I'll go with that.
Seems like the solenoids open in 1, 2 maybe 3 steps for softer right? So if you take the module out altogether its ok to do that, and it will just be firm?
And my idea for simply a single switch for all 1 solenoids, and another for all 2 solenoids will give a simple system, and not need of the module at all other than its connector to join 2? And no grief over error codes.
And some fun seeing how it behaves manually when I can tell what mode it is in. I always wanted this monitor thing to see what it was doing! Should have tried doing it ages ago when it all worked!.
I don't drive it a lot these days and lots of $ for dealer servicing is just getting a bit less fun. (Just put in a hoist in my garage to make it 3-car, and its great getting the SL up to a comfortable level to work on! Gets pretty close to the ceiling on the top notch. C250d wagon goes under)
Greg.
What a wonderful place to own a car like this. Just hop in and take a short coastal drive for some bearded green mussels.
I was thinking it rare for a V8 R129 to have ADS, but then ALL the cars originally sold in NZ got the option. There was an owner on the other Benz site that configured his ADS for what you are suggesting. His was ADS2 if I recall, but he was able to configure the valves like you suggest.
When my capacitors started to fail, the car would post an array of errors on startup. Once the capacitors warmed up and the car was restarted, everything settled down. Capacitors are inexpensive and not too hard to replace. Yours are older than mine and most likely due for a change out.
I have the ADS2 diagnostic pdf. You should be able to find the ADS1 version, but if you look through the document, it will mention the cascading enabling of the valves and how the system works overall. I can't upload the file as it is too big for my existing space on this site, but do a Google search on its name (r129-ads-ii.pdf) and you should be able to locate a copy somewhere.
the damper solenoid coils should have resistance 10 .. 16 Ohms each. If resistance values are ok, either your wiring or ADS ECU are not ok.
As Andreas suggests, changing the steering angle sensor (SAS) capacitors is worth trying (photo attached). New sensor is expensive but with luck used ones can be found (early W140 will do too).
I once connected temporary LEDs to verify my damper solenoids are working; driving over bumps made the LEDs blink. But I found no use for them after the ADS functionality was verified. Generally, keeping the car original is your best option - if it has not been molested already. ADS1 delivered top notch ride at the time of launch, 1989.
OK many Thanks for more info... Yes MAH we have some great places to drive here - thru the forests is fab with the smell and cool of the outdoors. SL is so quiet topdown.
Ever been to Milford? Did that last year and wow its a must-do with all those mountains. :}
If solenoids are not made to be powered all the time, does this mean that 'not-powered' is soft ?
Any error or code it goes full hard i believe, which is my problem, I want it normal / softer for comfort on our rough roads.
If 'solenoids on' is hard, then this violates the not allowed on all the time! I'm not sure what is right here.
If its soft and the solenoids kick in to harden it, then just taking the module out for a trial should confirm this. No one responded to this idea, does it seem ok!
Andreas seems you may know this perhaps from an inside MB position?
So the caps are in the steering wheel somewhere - is this a drama to get at? That pic is not part of the ADS ECU I have. Happy to replace those caps if I can get to them ok.
My solenoids showed all at 11.2 except 2 at 5.8 which is the rear ones with 2 in parallel as viewed down the cable at the controller. So look ok.
I have the ADS schematic and diag info from my Classic DVD which will get me voltages I can measure. But I don't think it has any disassembly info for the ADS related bits.
I would prefer to get it back to original, but I've already put a few cannon ***** in and its just getting expensive to keep doing all this for just a small no of km I drive in it. Dealer can do this, I am not really up for fiddling with the hydraulic part of it.
My C250d uses 1/4 the fuel for the same speed, actually has more torque, and gets most of my miles! But its not a convertible for those special days...
(If any of you can locate those other posts of interest let me know, I'll check them.)
Just to keep on topic, here is said car in Milford. Its another whole level up from what is in Queenstown. Tunnel thru the mountain around to the right under the snowy one.
Dug with picks and shovels and dynamite waay back in pioneer times.
These are some coils of the ADS 2, but the specification will be the same. ED = EinschaltDauer = duty cycle
Error or no power = fail safe = suspension hard.
I did not look at schematics, but i don't think there are two solenoids parallel. The charm of ADS is controlling every single wheel, not a pair of them.
Well Andreas, those are no damper solenoids in your photo; ADS1 has none of them. But ADS1 rear damper solenoids are connected in parallel as Greg states above.
Greg, I agree your damper solenoids (resistance values & wiring) seem ok. Sorry to say, your ADS ECU may(?) be fried. But try your luck and replace capacitors as mahunt suggests.
IMO you give no clue that points to a hydraulic problem in your suspension. You seem to have an electrical issue in the SAS and perhaps in the ADS ECU. I would never take my R129 to dealer. The only competence they have left with these older MBs (especially ADS) seems to be writing huge bills - at least where I live.
Thx for more comments.
My solenoids are about 1.25" dia by 2" long, chunky steel looking things.
I was hoping to clear enough codes to be able to observe normal behaviour even if only until the next code re-appears but I have to get past power on. I want to know what state is normal soft and hard and what changes dynamically.
No clues on the where the column sensor is, and removal? Don't like going in to the car without ideas as plastic is a bit brittle now and likely to smash important clips.
I'll do some more poking around this weekend.
Attached is two PDF documents that may help your poking a little:
- ADS1 ECU pin assignment. However it is for an early European spec R129, with manual ride height setting (I assume your Japan spec does not have that feature).
- Description of the damper valves. They have four different states where non-energized (default) is the hardest. When you select "sport" from centre console switch, one of the valves in each corner remains always closed.
Thx Pazo, confirms my feeling that the unpowered is hard and softer from applying the solenoids in a 2-bit 4 levels code.
And that they must be rated to run all the time, as soft is by definition all on, and the most likely state. Unless perhaps a middle state is used, and it goes either way depending on vibration to go softer. At least one must be on all the time anyway.
The pin connect you sent is actually like I've attached in the boxes match the schematic names- the power ? is actually grounded. I checked and these pins are hardwired to ground on the pcb. Even with power off.
I did briefly try to look at the TDF power drivers to see if one is dead, but even if I clear codes so it will try to wiggle those pins it in a couple of seconds finds an error and shuts off all action. So its just back to 2 switches one for 1 solenoids and another for 2 solenoids.
Also a bit puzzled that only 2 TDF chips x 2 outputs each =4 , but should be 6 solenoid drives. These chips are only rated to 2.5A so seems like they are a bit marginal. Rear pairs will be 2A so no useful margin.
More progress tomorrow, a lovely wet day here with an incoming cyclone - I'll be creek watching tonight, gonna get quite rowdy outside!
Ok so I can report I did get a manual control set up, after a false start using the wring power pin resulted in a xmas-tree of error lights.
I ended up cutting the connector pins near the pcb so I could keep existing circuits from fighting what voltage I applied.
1 switch for all the 1-soleniods and another for the 2-'s.
Had a driving test and it does make a difference to the softness, with a bit less harsh ride on sharp bumps and ridges.
I expected a bit more change to the steering roll, but could not really detect much. This was at modest speed not open highway, so suspect it may be more noticeable there, which I always felt anyway. And I think I still feel the real improvement delivered by this clever system was not that huge, given my Airmatic is super easy to tell mode you are in by the steering performance, but not this one.
So now no problem with clearing codes, its powered down! I don't think this interacts at all with the autolevelling part which is pretty much all hydraulic, but I'll try some things to prove this.
For some reason one of the switches in soft / activated brings up the ADS error light. But good news is for warrant of fitness tests I can make it go out by turning it off!
And anyway, if I do want to get it back to original, I now know it seems like I need a new ADS module as it errorred when I believe the solenoids are ok given they are the right resistance. If I can find a low cost option might get one as would be handier to swap in which is easy to do still. Learnt lots about it to boot.
Here's my little pcb with a couple of p-channel FETS and lead off the the Switch box in the cabin.
Hello Grege, please look for cold solder joints on the 35 pins of the connector of the control electronics.
Look very carefully with a good magnifying glass, because it is very difficult to see.
Often the contacts of relays and valve coils are soldered out, and lead to loose contacts on Mercedes electronics.
Hello Grege, please look for cold solder joints on the 35 pins of the connector of the control electronics.
Look very carefully with a good magnifying glass, because it is very difficult to see.
Often the contacts of relays and valve coils are soldered out, and lead to loose contacts on Mercedes electronics.
It is correct, if an error is in the ADS, it is switched to hard damping.
02-05-2022, 05:57 PM
