aegea

Hi Guys:

I added a 2004 SL500 AMG sports package. Will you please help me restore this Brilliant Silver Metallic beauty?

I installed rebuilt front and rear valve blocks and all 4 new accumulators. Mainly the right rear goes too low and the right front raises too high. I have gotten the C1526-2 Fault in hydraulic circuit at front right suspension strut DTC since before the valve rebuild. Does this mean I need to replace the front right strut?

Previously the left rear got low; and now I get the C1525-4 Critical vehicle level rear left DTC. I thought rebuilt valves and new accumulators would fix that. Could I have installed a line or connector wrong? With the color coding matched up, it seems unlikely. Should I replace the right front strut first, and see if it corrects everything. Can a rebuilt valve be sticking or something?

I have spent several days cycling ride heights through 0,1,2; sport mode on & off, running over speed bumps, disconnecting both batteries, reconnecting. The right front always returns to the highest position, the left rear goes low.

What can I do?

All my best,
Thom

Tom Manning

This is just a guess.

Could one of your level sensors at the front be faulty? Since the strut is in effect a passive reservoir, the strut itself is unlikely to be causing the front to rise up. Be cautious about replacing parts with inadequate diagnosis, but the level sensors aren't expensive

***

It's not unusual to rebuild a valve block and find it still sagging. It can be tricky to get it all to seal and perhaps that, independent of the front issue, is causing the rear to sag.

Dr. Plastic

What Tom said. You may need to check for codes related to the sensors. Try running a Rodeo and or calibrating thesuspension on a flat and level surface.

Dr. Plastic

06-04-2018 3:43 PM PID24BE © Copyright Daimler AG Page 1/2 Level Adjustment Without Obvious Cause

Tom Manning

For your front issue, have a read through this:

https://mbworld.org/forums/sl-class-...ngine-off.html

The pump retains pressure for a time after the engine is off: you most likely have an issue with the control valve for that corner, allowing fluid under pressure to be pushed into the strut.

This to me would also indicate that the blocking valve for that corner is also faulty. But I'm starting to think that the blocking valves, which prevent fluid from the struts from finding its way back to the tank, do not work the other way; they can allow fluid from the control valves into the strut, via the 'locked' blocking valve.

For your rear issue, it's probably contaminants in the blocking vale for that strut, causing a leak back to the tank.

aegea

Hi Guys:

Thanks for the great tips. I am sure we will get me through the hydraulic suspension fix; and I will post results. I am reading advice and linked posts.

What is a reasonable way for me to get Star diagnostics? Can I buy a complete ready to use scanner-like tool? Should I dedicate an old and slow outdated PC to load old cheap STAR, ETC.? Can I use STAR on a new state of the art Windows 11 Gateway PC with plenty of memory and RAM? (I am posting live chassis data below from my Autel Diaglink; but I don’t think voltage from level sensors, strut height, etc. helps me diagnose bad level sensors.) Can STAR program a replacement PSE, ABC Control Module? Can STAR detect bad Level Sensors, Struts, Valve Blocks, etc.? Can STAR perform ABC calibration, rodeo?

For now, can I install new cheap ABC level sensors or other cheap parts, and hope for a fix?

How do I flush fluid? Can I just open all 4 bleeder valves? Can I use Lubegard complete synthetic power steering fluid # 23232? Amazon shows it compatible with my car. The bottle says it is PENTOSIN CHF compatible. If not, is there an inexpensive hydraulic fluid available?

Today the Autel Diaglink added C1526-16 Malfunction in pressure supply
to the already mentioned C1525-4 Critical vehicle level rear left C1526-2 Fault in hydraulic circuit at front right suspension strut

V from the level sensors ranges from 2.1 to 3.78 see readout data below:

12062022 2004 500SL DTCs and Live Data from Diaglink:

Read Codes

C1525-4 Stored

Critical vehicle level rear left

C1526-2 Stored

Fault in hydraulic circuit at front right suspension strut

C1526-16 Stored

Malfunction in pressure supply



---------------------1 of 35 Frame---------------------

100 B22/8 (Left front level 2.10 V

sensor)



111 B22/9 (Right front level 3.78 V

sensor)



113 B22/7 (Left rear level 3.00 V

sensor)



115 B22/10 (Right rear level 2.82 V

sensor)



---------------------12 of 12 Frame---------------------

402 B4/5 (ABC pressure sensor) 188 bar



---------------------6 of 7 Frame---------------------

140 B22/4 (Left front plunger 55 mm

travel sensor)



142 B22/5 (Right front plunger 0 mm

travel sensor)



144 B22/1 (Left rear plunger 86 mm

travel sensor)



146 B22/6 (Right rear plunger 81 mm

travel sensor)



---------------------10 of 10 Frame---------------------

110 Left front vehicle level -6 mm



112 Right front vehicle level 56 mm



114 Vehicle level at rear left -63 mm



116 Vehicle level at rear right -8 mm



---------------------1 of 12 Frame---------------------

221 Terminal 30 14.0 V


178 Terminal 87 ON

mythos0512

I can tell you that the right front plunger at 0mm means its not reading. That is the sensor in the strut. Under the hood where the strut mounts you should see the electrical connector to it in the middle.

aegea

Thanks... good observation... what should I do?

I removed and reconnected that electrical connector and found no change. Is the strut bad? Don't I need to disassemble the strut to change that sensor? If so, I will probably get a used replacement. Do the level sensors have anything to do with the strut sensor problem?

I found bailing wire holding the strut connector together. See picture. So, I would get a strut with the hose still attached.



Does that picture help anyone with problem diagnosis?

mythos0512

That fitting looks horrible. It is a quick disconnect fitting. It looks wet like it could be leaky? I would examine other parts of the ABC to see if other parts look like that, it means somebody didn't know what they were doing when working on it. I know on mine it took a lot of force and 3 tries before i got it to finally seat fully.

I will leave it up to you on what to do with the strut. In my case with my sl500 the plunger was bad on the rear, i found just the sensor for sale (i think ebay) and replaced it on the strut. It worked. Then the strut started leaking (not from the sensor) so I had to replace the strut in the end. If i had to do it over again I would've just bought the rebuilt strut from Arnott.

aegea

Thanks... I hope the connector not attached to the hose on the strut side is okay, so I hope to get the hose connected to the strut. Can anyone tell from the picture or experience which connector side is causing it to be wired together?

Tom Manning

That fitting looks horrible...

That fitting is a disaster waiting to happen. I would remove the hose, cut the pipe in the straight section, fit a compression fitting and have a new, slightly longer hose made up. They're not expensive at a hydraulic shop. Alternatively still cut the pipe and install the compression fitting but replace the rest with parts from a wrecker.

If your strut is not leaking, no need to rush and replace it now, but it seems you have an issue with the plunger.

aegea

Isn’t the chassis live data: “B22/5 (Right front plunger 0 mm travel sensor)” problem causing the front suspension problems?

Tom Manning

Problems are relative.

Blowing a hose on the freeway at speed is a problem: you cannot drive the car without ABC pressure; this is one big drawback of the R230 chassis. The car will then have to be towed, and if you don't take the bumper off at that point it will probably be damaged being winched up on the flatbed. Just sayin'. Problems compound.

Replace that fitting when you replace the strut! Fencing wire was engineered to restrain Texas Longhorns, not the 2800 psi of pressure our pumps put out. That farmer who 'repaired' that line should stick to fixing tractors.

aegea

Right you are!!!! I think I should just get a used strut with a good hose attached for replacement. Is the zero travel reading from that sensor causing the front suspension problems? Will the new strut and hose solve the front end problem?

Tom Manning

I don't know for sure..

I think that's your issue though, looking at the data. And that the plunger sensors can't be replaced without changing the strut (unless anyone knows of a work around that's been done).

That's what I would do: buy a used strut, or replace them both with rebuilt units.

My concern is the quick release connector that's been wired up. Also those rubber mounts that clamp the lines are an important part of NVH damping and need to be properly oriented and mounted to avoid vibration.

MikeJ65

1) The strut part of the quick connect is probably fine. If it won't stay lock or stay locked, the most likely problem on the female (line) end.
2) I don't know if all of your data was collected at the same time, but if so, the voltages, heights, and strut plunger readings are very inconsistent. This might be a calibration problem. Generally speaking, the height should be near zero at 2.5V. This varies a bit with calibration, but it shouldn't be off more than .2 or .3V.
3) Is the right front always at full height, or does it just go there when you shut the car off? If it lowers, but you never get away from the 0 reading on the plunger sensor, you have a bad sensor, wiring, or controller. Normally, however, the control will detect a bad sensor and put the car into limp mode (fully raised).
4) Try the strut actuations (if your Autel will do it). Make sure that each strut will raise or lower manually with the actuations. If so, retest with blocking valves closed. This will give you a very good idea of the actual condition of the valve blocks. Nobody rebuilds the control valves, they cannot be disassembled. While it is common for the o-rings to leak, these o-rings only seal the valve in the housing. There can still be internal issues in the valve itself.

aegea

Thank you, guys, for the great analysis!

The right front strut stays at its highest point always. I have always seen the left rear at its lowest point. (It may move up while I sit inside the car and push raise and lower buttons… I don’t see that.) So, max height and the: B22/5 (Right front plunger 0mmtravel sensor live data reading indicate a bad internal strut travel sensor, right?So, I can find a used strut (with male quick connect hose attached) and replace the right front strut.

Since the female side of the quick connect is likely the faulty component, and is attached to the metal hose containing the bleeder valve, should I buy a used female quick connect/bleeder valve hose? Can I unscrew the female quick connect, and just replace it? Does anyone have those part numbers, and/or sources for purchase?

Note: The left front strut goes to full height; but sunk down to normal/middle height overnight.

aegea

Because of an opinion that the female coupler may be preventing flow-through, another that the corresponding line is bad, and that the fact that the coupler must be fixed to be safe, I ordered a new female coupler/bleeder line.

I want to expedite fixes, but with all the money I am spending on restoration, I don’t want to pay for expedited shipping, or an unnecessary strut. So, it may be awhile before I can update. I hope I can replace that line and at least solve my front end suspension problems.



Thanks to everyone for the great analysis so far.

aegea

Hi Guys:
When I open the driver door in the morning, and sometimes randomly the front and/or rear valves (4 per valve block) click multiple times for several minutes, then stop clicking. Does this indicate a specific problem??????
See above for background, especially – I replaced the front and rear valve blocks with rebuilt units. I replaced the 4 accumulators. Could I have reattached the lines wrong? I get fault codes:
C1526-16 Malfunction in pressure supply
Ongoing codes:
C1525-4 Critical vehicle level rear left
C1526-2 Fault in hydraulic circuit at front right suspension strut.

aegea

PRAISE BE TO THE LORDS OF R230!!!!! You guys are the best.

I replaced the hose with the sloppy work on the connector – front right strut to valve block, and voila! I am riding level with no more ABC warnings. The low left rear problem is a pigiback resolution. The front right high corner and the left rear low corner were both fixed with the front right hose replacement.