MImagna

Hello,

My car has been laid up for 2.5 month with a variety of problems. My current problem is that after the car has had new ABC hoses, and the valve blocks refurbished and working, and new accumulators put in. The driver side rear will not lower. The vehicle appears to think at max height it is level.

s their anyway to get the ride height sensors to default back to factory?

My garage has attempted to reset the the values for the ABC. The front resets fine. When they get to the rear, the program tells them they are out of specs and does not allow them to put in new specs for the ABC.

Any help is greatly appreciated. Where I am it is almost time to put the car away for the winter.

Regards.

HLG600

Is your shop accessing the system with Xentry or a different diagnostic tool?

MImagna

They are using an Autel Scanner. They may have access to the Snapon scanner or a Matco. Will any of these work?

HLG600

Their pro-grade scanners should work, but Xentry is the ideal tool.

Where are you located? Maybe there's a member nearby with a setup that can help.

MikeJ65

With a pro grade scanner, they should be able to actuate the control valve on that corner and raise and lower the corner. If it won't lower, or starts raising again with the valve controlled neutral, odds are that the valve is bad and letting high pressure fluid into the strut when it shouldn't be. If that checks out, they can check the ride height sensor values and strut extension values and see if they make sense. BTW, it should not be necessary to recalibrate ride height if the struts and height sensors were not disturbed. Hoses, valves, and accumulators do not alter the calibration.

MImagna

Thank you. I passed this onto the garage. Hopefully Monday will bring good news.

Much appreciated.

MImagna

I am in Western NY. If anyone has the Xentry and is able to provide support please let me know. I have unfortunately not had the use of my car since July.

Speed750

I've scanned mine with a Snap On scanner. It wouldn't reset values.

MImagna

The plot thickens. When the car is turned off, it "jumps" to the highest position. I have bought the xentry diagnotics. Does anyone have any recommendations on how to review this problem?

MikeJ65

It sounds to me like you have two problems. Each strut has a proportional control valve that cycles between levels of feed, drain, and blocked and a blocking valve that is supposed to block any flow to/from the strut when the car is parked (ignition off). I suspect that you have a pressure leak past the control valve and a blocking valve that is leaking or stuck open.

If you go into ABC actuations, you can control both of these valves manually. If I recall correctly, the blocking valve terminology is a bit confusing, on being open (unblocked). If you turn the blocking valve off (F4), the strut should not move, even if you actuate the control valve. If you get movement, either the valve is leaking (most likely), or it is stuck open. To test the control valve, turn the blocking valve on (F3, unblocked) and actuate the control valve in each direction (F5 & F7). The corner should raise and lower with about equal speed. Next, put the valve in the neutral position (F6), the strut should not be moving. Any movement with this setting means that you have an issue with the control circuit, most likely bad o-rings on the valve. You will also be able to see the actual current to the control and blocking valves. The blocking valve should be within range, the control valve should be near zero with the car running and stationary. If you have a control valve leak, it will be fighting that leak and not in the neutral position.

You could try a rodeo or a filter procedure in case the issue is contamination, but I think you will end up pulling the rear valve block again. You can also look at the strut plunger and ride height sensor values and see if they make sense and, of course, start by checking ABC codes.

Mike

bobterry99

If it does this immediately upon switching off the engine, then you your problem is certainly a failed front level control valve. One possibility is a broken spring -- there are two, and they are responsible for closing the control valve when no electric current is supplied to the valve.

If your car does not sag, then the blocking valves are okay. Despite having working blocking valves, your car is able to jump because unlike the control valves, the blocking valves unconditionally remain open for a brief time after the engine is switched off.

Dalplex

The block valve as NO valve can be stuck open. In this case, fluid can not flow either way, that means can not flow out from struts, to lower the height.

There may be a check valve malfunction in similar fashion that can not let fluid out from struts too.

In both case, control valve, even was function as normal. Can not control the height.

Try applying voltage to the block valve solenoid directly, monitoring any click sound from valve. Or any current change from this dc supply. This will identify the solenoid situation.

Same method can apply to all solenoids of all/any valves, basically back to 60’. That manually control without computer’s help.

MikeJ65

Bob, Thank you for the clarification, I did not know about that blocking valve delay. I think we do both agree that this is almost certainly an issue with the valve block.

Mike

bobterry99

When the engine is switched off the ABC controller monitors the level at each corner and corrects for changes in level if/when the vehicle is unloaded. According to Mercedes' functional description of ABC level control in the WIS it does this for about one minute, I recall.

I wouldn't think it possible for a valve spring to break, yet kbob999 reported finding one a while back. More recently, a friend had the exact issue as the OP, and in his case a valve return spring was missing -- the functional equivalent of a broken spring. The valve block had been disassembled by a previous owner and then reassembled without one of the springs.

Theoretically I suppose the suspension may jump as a consequence of an errant input to the ABC controller, but that seems almost implausible to me. Still, if Star Diagnosis is available, as others have mentioned I would look at the current to the control valve of the affected strut and ensure that the controller isn't causing the action. A positive (+) current to the control valve extends the strut to raise the car, while a negative (-) current to the valve retracts the strut to lower.

MImagna

Thank you all. I have printed the information and will bring it to the shop. Again with any luck we will be able to narrow down the problem and get it fixed before the snow falls.

getspankedent

Got tried of repairing ABC system. Just installed new system still dialing in system to my comfort.

Dalplex

How much the cost?