mrbobby

Do we have any AMG ABC experts on the forum? I have an '04 S55 that has periodically been displaying the ABC - visit workshop message. There is no fluid leakage so I'm assuming that the struts are OK.

Yesterday the white ABC warning came on shortly followed by the RED ABC warning. The car dropped on the rear and the tires began to rub. I pulled over and shut off the car. I cleared the warnings with the "r" (reset) dash button. The car was sitting down on the rear tires. I restarted the car and after approximately 30 seconds the car rose on its own and assumed a normal stance.

About 6 hours later I drove the car again and received both ABC warnings but the rear did not drop down. This AM the car was sitting normally when I stated it and drove it for about 10 miles with no warnings or dropping. After finsihing this appointment (approx. 1 hr.) I drove for another 7 miles and the lights came on and the suspension dropped on the rear to settle on the rear tires. I was in the store for 5 minutes and came out and started the car. The car remained on the rear tires until I pushed the raise button on the dash. The ABC red warning now showed car rising and then the warning disappeared and up came "no malfunctions.

Now for my question. Does this indicate a pump going bad as my Indie tells me or is it a sensor or electrical problem as it seems to me?

mrbobby

Now it's sitting close to the front tires. As I stated earlier, there are 2 ABC warning signals in the cluster, 1 white and 1 Red. I now believe that the white signal indicates the vehicle is settling ion the front or rear while the red signal tells me that it is sitting low on a 4 corners. Can anyone confirm this observation?.

Welwynnick

It sounds like the valve blocks rather than the pump. If the pump was failing, it wouldn't raise back up. You've probably got some sort of contamination in the fluid in the valves. This is much less painful than a bad pump. There are lots of thread about this, like these:

https://mbworld.org/forums/cl55-amg-...ock-today.html
https://mbworld.org/forums/s-class-w...2003-s600.html

First thing to do, though, is check the fluid level in the reservoir. Its the large one next to the power steering reservoir.

Nick

mrbobby

The fluid level is correct. I just had my Indie do a fluid change. Never had the problem before but coincidences do happen. I'm guessing there is contamination in the system from the fluid change. What do you think?

Welwynnick

Did the problems start when you had the fluid change?

Do you know if your indie did the rodeo when he flushed the fluid?

Nick

mrbobby

Yes, there weren't any suspension problems before the fluid change. They told me they did a rodeo procedure. I'm convinced it can't be the pump because I can use the dash button to return to proper height/operation.

Welwynnick

I think you need a better Indie.

There might possibly be some air in the system, but its probably contamination. As long as the reservoir is full and the pump isn't making any audible noises, it should help by repeatedly raising and lowering as you drive along, which is a sort of DIY rodeo. That may help to clear the rubbish out.

Otherwise I think you need to remove the rear valve block and clean out the valves, and I would replace the O-rings while you're at it. Its not that difficult.

Whatever you do, don't go to a dealer or believe anyone who says you need a new pump or valve block.

Nick

mrbobby

Thanks for all your help. I think you are right on the mark. I'll continue trying the modified rodeo trick. Do you think another Star rodeo function might clear the blocks?

MB-Dude

Mr. Bobby,
Out of curiosity, did the Indie replace the ABC filter when he did the fluid change? There is an uber-fine mesh filter in the ABC reservoir that should be replaced with fluid changes. Perhaps some contamination on the filter was disturbed during the fluid change process, especially if the filter was pulled out and the reservoir was not drained prior to the fluid change. Nick is right, the ABC circuit is wickedly susceptible to valve block contamination.
Cheers,
Jeff

maw1124

.

Bob, +1 on this thread. I've just finished going through this on my car, but not in MI, as the car was in FL at the time. It's the valve. Not a cheap part, but a very well known problem and procedure. I think Mercedes rec is actually to address the fluid as a first step, and if the problem re-occurs, to address the valve. It's not the pump.

Good luck, and let me know how it turns out.

Cheers,

maw

mrbobby

he more I look at this issue the more confusing it becomes. Since the car doesn't sag over a period of time I'm having second thoughts about seal damage in the blocks. There has to be a sensor that controls the application of the hydraulic pressure to each of the tires/wheels under different situations or demands. I'm starting to think it is a sensor or electrical problem. Please tell me if I'm crazy and running down the wrong path but it is real easy to throw money at this problem and still be no further ahead. I don't mind spending a dollar but I sure as H--l hate wasting money, if you know what I mean.

mrbobby

Just an update - I've been cycling the car through dash originated up and down when the opportunity presented itself over the last couple of days. Knock on wood I haven't had any ABC dash light or failure issues over the same time period. I beleive thqat either the cycling has removed any air trapped in the system or has flushed any contamination into the filters. Any comments?

MB-Dude

Reasonable possibility. I'd maintain guarded optimism. Regardless, sounds like your situation *may* be resolving itself. [Fingers crossed.]
Cheers,
Jeff