SL-Class (R230) 2003 -- 2012: Discussion on the SL500, SL550, SL600

SL/R230: ABC plunger sensor replacement without strut?

Old Sep 13, 2022 | 02:18 PM
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ABC plunger sensor replacement without strut?

I recently started getting an intermittent ABC/Visit Workshop message. Scanned with an iCarsoft tool gave me a C1128 - Fault in component B22/1 (left rear plunger travel sensor) as well as a P112801 (not in database).

I read the values on the plunger travel sensors, 3 were in spec around -40 -60, the rear left was stuck at 255. I took the sensor out, cleaned the connectors, opened up the case to inspect for any visual abnormalities, everything looked ok. Put it all back together and the code was gone for a day and plunger heights read in spec. Now it is back again reading stuck at 255.

To me it sounds like a bad sensor. I started looking around to replace it but it looks like it is sold with the strut assy only ($900+). I see a couple on ebay sensor only with the plugs cut off for $200+. Any advice or recommendations without going out and buying a whole strut?

R230 04' SL600
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Old Sep 13, 2022 | 04:32 PM
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Is this the part you are looking for?

level sensor



Also video of replacing it.


Last edited by g0rsq; Sep 13, 2022 at 04:35 PM.
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Old Sep 13, 2022 | 05:32 PM
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Yes, that is the sensor I am looking for. $280 usd plus core charge for used seems pretty steep considering there are used complete ABC strut assy's for $100-200 more
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Old Sep 15, 2022 | 02:06 PM
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You don't see them separated too often. I do happen to have a spare. When I got my 03 SL500 I had the same problem, I found one used and paid about that same price, it did fix the problem. A few months after the strut started to leak so I replaced it and returned the bad sensor on the core, leaving me the used one as a spare. I'd be willing to let it go, come up with a price and zip. Message me if interested.
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Old Jan 8, 2024 | 09:55 PM
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Installation Proceedure

Originally Posted by mythos0512
You don't see them separated too often. I do happen to have a spare. When I got my 03 SL500 I had the same problem, I found one used and paid about that same price, it did fix the problem. A few months after the strut started to leak so I replaced it and returned the bad sensor on the core, leaving me the used one as a spare. I'd be willing to let it go, come up with a price and zip. Message me if interested.
Hi mythos0512,
When you installed the used one, did you have to recalibrate or reprogram for the new sensor? I need to replace one out as well, and am wondering what is required. I've had mine out a couple times trying to see if reflowing solder would bring it back but so far no luck.
Thanks.

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Old Jan 8, 2024 | 10:13 PM
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In theory, you should recalibrate. However, my experience is that they are pretty close out of the box and it probably won't be far enough off to matter.
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Old Jan 8, 2024 | 11:07 PM
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Originally Posted by MikeJ65
In theory, you should recalibrate. However, my experience is that they are pretty close out of the box and it probably won't be far enough off to matter.
Correct, I did recalibrate when I changed the sensor. It was the first time messing with the abc suspension. I've since replaced 2 more struts and I didn't recalibrate since they were the correct height after the change.
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Old Apr 17, 2024 | 08:15 PM
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Plunger sensor....

Hello, have a 2005 SL500, did a solenoid block rebuild, both front and rear. Replaced all the actuators, (all nitrogen-filled parts). Rodeo, clean fluid using MBStar. When it came time to calibrate, it won't accept the values. I did the Plunger travel sensor calibration, it extended all 4 struts, and after I took readings, and am finding consistently that the left rear numbers are concerning. I have attached the numbers from MBStar in MM and then another tool in inches.
I would like to hear the least expensive DIY "MacGyver-like" options. I was at first thinking of height sensors, as it seems the voltage is off, but I can't make the left rear strut move during calibration. That is due to the plunger problem I am thinking? I can make the voltage change in the height sensors, taking them off their mounts, so I'll look forward to any help.
Mike? Anyone?
Thanks in advance!



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Old Apr 17, 2024 | 09:06 PM
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Those are some pretty odd numbers for strut plungers. To calibrate, the car is fully raised and that sets the zero position. With the car at normal height (in the vicinity of -4mm level), your strut plungers should be in the 45mm range. As you raise it to the highest position, strut numbers should come down closer to 20mm. That 86mm reading would be fully dropped on the left rear, if it even has 86mm travel.

I would start with checking level, plunger, and wheel well heights at normal and fully raised levels. I think you either had an improper calibration or something is not put back together properly from the work you did.
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Old Apr 18, 2024 | 11:06 AM
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Can't get LR strut to move

Originally Posted by MikeJ65
Those are some pretty odd numbers for strut plungers. To calibrate, the car is fully raised and that sets the zero position. With the car at normal height (in the vicinity of -4mm level), your strut plungers should be in the 45mm range. As you raise it to the highest position, strut numbers should come down closer to 20mm. That 86mm reading would be fully dropped on the left rear, if it even has 86mm travel.

I would start with checking level, plunger, and wheel well heights at normal and fully raised levels. I think you either had an improper calibration or something is not put back together properly from the work you did.
When I go to calibrate I try to get all voltages close to 2.5, then split the difference in values between - 8.4, - 7.4 and - 2. 4, - 1.6, then go to save it it says not within acceptable levels. But I can't get the LR strut to respond unless it's in the rodeo or plunger sensor calibration movement.
How can I zero out level sensors, recalibrate them, or other suggestions. I can't go on to load calibration and and such it goes to the previous crazy calibration and the cars is undrivable.


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Old Apr 18, 2024 | 12:33 PM
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With the car running, cycle through height adjustments and stop at the lowest setting. Then go into the ABC module and print vehicle level, level voltages, and strut plunger screens from DAS. Take a tape measure and record all four wheel well heights. Then hit the height button twice to get to the high setting and repeat all of the above. I'm trying to figure out which components are working and if there are some that are not. I can't tell anything from one piece of the puzzle without knowing what the other sensors are seeing or the actual suspension height. Your DAS screen would indicate the car is in an extreme lean with left side being 4-5" lower than the right.
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Old Apr 18, 2024 | 01:31 PM
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I think it might be a solanoid

Originally Posted by MikeJ65
With the car running, cycle through height adjustments and stop at the lowest setting. Then go into the ABC module and print vehicle level, level voltages, and strut plunger screens from DAS. Take a tape measure and record all four wheel well heights. Then hit the height button twice to get to the high setting and repeat all of the above. I'm trying to figure out which components are working and if there are some that are not. I can't tell anything from one piece of the puzzle without knowing what the other sensors are seeing or the actual suspension height. Your DAS screen would indicate the car is in an extreme lean with left side being 4-5" lower than the right.
The left rear solonoid is getting the proper power. However I can't make it move up or down. Which color is the left rear on the block blue or green? It's not moving unless it's in rodeo or plunger height calibration. It moves.
It was a car from the auction and the calibration is way off. So when I got go to calibrated level it's fouled up.
I will do your suggested measurements and respond later thus afternoon. I wish I could spend all day on it.... But I'd really have no hair left. Ha!
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Old Apr 18, 2024 | 05:20 PM
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Response to MikeJ's questions

Tth


These are at the lowest ABC in-car setting LF 16", RF 12-1/4", LR 17", RR 13" from the center to the fender.
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Old Apr 18, 2024 | 05:26 PM
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2nd response to MikeJ

These are the highest in-car LF 17-1/4", RF 13", LR 17", RR 12-3/4".
When the vehicle is off the heights from the fender to the center are LF 14-1/2", RF 14", LR 14", RR 13-3/4"





Last edited by JamesMBZ; Apr 18, 2024 at 05:50 PM. Reason: Additional numbers
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Old Apr 18, 2024 | 06:04 PM
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Oh PS Mike I checks the amperage to all of the solonoids and they are getting the miliamps prescribed for each.
The only DTC codes I'm getting are failure to calibration and failure of load calibrate. That's it.
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Old Apr 18, 2024 | 11:12 PM
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The numbers are at least all consistent. The fronts are moving in the right direction, but the rears are locked full low on the right and full high on the left. Have you tried to actuate the individual rear struts? You should be able to fully raise and fully lower each corner by actuation. Don't forget to open the blocking valve before operating the control valves.
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Old Apr 18, 2024 | 11:15 PM
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Originally Posted by MikeJ65
The numbers are at least all consistent. The fronts are moving in the right direction, but the rears are locked full low on the right and full high on the left. Have you tried to actuate the individual rear struts? You should be able to fully raise and fully lower each corner by actuation. Don't forget to open the blocking valve before operating the control valves.
I have tried to move them from the calibration screen. How to unlock the blocking valve? I couldn't move the RL.
I can move the RR
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Old Apr 19, 2024 | 11:07 AM
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Originally Posted by JamesMBZ
I have tried to move them from the calibration screen. How to unlock the blocking valve? I couldn't move the RL.
I can move the RR
I decided to run the rodeo motion to see if they all moved. They indeed did.
Do i need to run that to completion?
All so it seems to have left the heights and voltages in a better place, so I tried a calibration and it accepted the numbers but to complete the process you have to to the load calibration which lurched the car left and lower front left. However it said success, and then seemed to go to normal levels. I stopped the car. Left it over night. We'll see how it goes today, if it's driveable etc.
The plungers mm travel is a concern and I think the reason for the load calibration action. Mike?? Thoughts.... What's broken here....
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Old Apr 21, 2024 | 10:22 AM
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I would go to actuations and try moving each strut up and down individually. Make sure that the correct strut is being controlled and that movement is in the correct direction and proportional to the input signal. Lowering is faster than raising, but all four struts should be acting roughly the same as you go through this. This might not uncover any issues, but at least you will have verified the correct wiring and plumbing and valve function.
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Old Apr 21, 2024 | 01:20 PM
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I have tried that. The left rear doesn't move during the rodeo.
I will go back into the block and make sure no oil in the connection.
The power is registering at the solonoid.
How can I know without swapping one out we there it's no good. Is there an ohm test for one?
Mike off topic briefly, 2004 SL55, the passenger seat weight sensing module can't communicate with mbstar. This srs light on. Fuse or ground, I'm going to help him today if I can... Thoughts? It was working before we did the 100A fuse in the footwell for battery issues....
Thanks man!
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Old Apr 22, 2024 | 03:12 PM
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The best was to test the solenoids is to just actuate individual struts and make sure that they move as they should. You can also close blocking valves and test that they block travel.

As far as the WSS, check the yellow connectors under the front edge of the seat. I think there are two on the passenger side, one for WSS and one for the seat belt retractor. The WSS ground point is W36, which is the passenger floor ground in front of the CAN distributor. You shouldn't need to mess with it to get to the firewall fuses, but it could have been removed inadvertently and not replaced or the wire for the WSS left off.
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Old Apr 25, 2024 | 12:12 PM
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Mike, you know I appreciate your vast R230 programming knowledge, but thanks again!

Latest, I checked control solonoids on the rear block. Cleaned the contacts. I was able to regain individual height control on Tuesday. Very excited about that. Then on Thursday (no activity on the SL) no control.
However, when I go to rodeo mode, I get full motion on all 4 struts.
So I stop rodeo it leaves the car in a position to go into the 3 functions required for a successful calibration. 1. Plunger calibration. I get a successful message from DAS. 2. Calibration, I get voltages in range(around 2.5) and then used - 8 and - 2,. As a result I get a successful calibration message. 3.Load adjustment - when I hit F3 the car lurches low and left ( a bit lower in the front, but it's listing left at about 30 degrees), then it normalizes to what I calibrated at and says successful load adjustment.
So I thought it adjusted and accepted all of the items needed for a successful outcome.
Well when I stop the cars engine it settles to a good locked level. But when I start it again it goes to the left listing position.
Why is the module not saving my input? Does it sound like a corrupted module N51/2?? This thing is not behaving arghhhh.
Thanks in advance,.
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Old May 2, 2024 | 03:51 PM
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Switched out ABC control module, as I found one for 50 bucks on eBay. The biggest thing that's concerning me is that I am not getting any DTC codes and they have a code for almost everything. I'm only getting codes that are obvious, too low in the left front kinda thing.
So when I go to individual actuations and I power the blocking solenoid and operate the control solenoids, they all do as they should except the left rear, when I hit the lower F10, it went up!
Also, it did a full rodeo with all struts in full motion. Then pitch motion with full front and rear motions.
However when I do left and right motion it only lowers on the left. So no lowering to the right.
I'm at a loss. Is this a sensor issue, a solenoid failure, an electric wiring problem on the solenoid.
lastly if i clean the plunger sensors, they pull off the top. Do i need to depressurinse the system before pulling on off?
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Old May 3, 2024 | 10:47 AM
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Did you try raising the left rear to see if it lowers instead? That would indicate switched wires. It is possible that someone broke a connector and put the wires back in backwards. Probably more likely that you just have a bad control valve.

You can bleed the pressure on the strut lines by opening the bleed valves in each wheel well. If they are rusted, don't risk twisting them off, just slowly unscrew the lines at the valve block instead of the quick connects. You won't be able to release the quick connects under pressure.
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Old May 3, 2024 | 07:38 PM
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Thank you for confirming my thinking, yes I did try to lower it. It wouldn't do anything. The weirdest part is that the control valves operate properly when called upon in a routine, like rodeo or pitch routine front to back. I get full motions. However, I get an intermittent response from the left rear strut when singled out in actuations menu.
Also, the new control module showed a 9 constant 9 milliamp signal on the right rear control solenoid. So between the 2 iassues I think that's where most of the problem lies. Can the control valves cause problems and not throw codes? I'm not getting any codes except the obvious ones as I said like left front too low.

I swapped the left rear level sensor with the right side, but go significant changes, however, I still think the rear-level sensor is suspect. The reason is that the routine called "roll" makes it go center to right only, before I switched the sensor it went center to the left only. In both scenarios, I didn't get full left to right motion. After I switched the sensor and did the "roll" it went center right only. That was curious. I'll probably confirm that before we spend 80 bucks for a new sensor. By running roll and then switching it back and running roll.

Thank you very much for your insights. I've discovered that the control solenoids should give a 4-5 ohm reading on the bench to check them. Thoughts?
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