SL/R230: R230 ABC problem - Wheel Sensor (I Think...)
05-28-2019, 07:59 AM
#1
Member
Thread Starter
R230 ABC problem - Wheel Sensor (I Think...)
Good day everybody. The SL500 knows I want to sell it, so it's playing up... The left front wheel is right down on its stop, and won't rise at all whatever the suspension setting. .
I'm using an iCarsoft diagnostic tool. The level sensor on the LF corner, engine running, shows only 0.47 volts; the other three are all between 2.49 and 3.06 volts.
The LF vehicle level shows as 113 mm; the RF is -1 mm, the LR -38 mm, and the RR 7 mm. The car is not standing on a perfectly level surface, though. Pump pressure stays at 173-175 bar.
I haven't checked the connection yet, but assuming that's not where the fault lies, a replacement sensor seems likely. There are lots of them out there, all with the part number 0025428818, but many of the ads call them headlight levelling sensors. Can anybody confirm that that part number is correct for the ABC levelling sensor too? And finally, once I fit the replacement sensor, will I need to get the car on a Star to dial it in, or is it plug n' play?
I'm using an iCarsoft diagnostic tool. The level sensor on the LF corner, engine running, shows only 0.47 volts; the other three are all between 2.49 and 3.06 volts.
The LF vehicle level shows as 113 mm; the RF is -1 mm, the LR -38 mm, and the RR 7 mm. The car is not standing on a perfectly level surface, though. Pump pressure stays at 173-175 bar.
I haven't checked the connection yet, but assuming that's not where the fault lies, a replacement sensor seems likely. There are lots of them out there, all with the part number 0025428818, but many of the ads call them headlight levelling sensors. Can anybody confirm that that part number is correct for the ABC levelling sensor too? And finally, once I fit the replacement sensor, will I need to get the car on a Star to dial it in, or is it plug n' play?
05-28-2019, 02:38 PM
#2
Banned
Why? If you were studying mechanical engineering at MIT would you bring a slide rule in lieu of a calculator to a final exam?
Since the output voltage of a sensor is proportional to height and the car is low at the left-front corner, 0.47 volts is eminently plausible. I believe the sensor is fine.
I suppose you believe this because the level at the left-front corner is reading 113 mm when intuitively you'd expect to see a large negative value. But if this is the case you must understand that the level is derived by software running either in the ABC controller (likely, to me) or in your iCarsoft scanner. Further, I suppose the implausible 113 value could be a consequence of iCarsoft misreading a memory location from the ABC controller. Whatever, it seems to me the level sensor is not responsible for "113".
Yes, you would need Star Diagnosis to adapt your new sensor to the system by executing ride height and level calibrations.
If this were my car the first thing I would do is use Star Diagnosis' to have ABC adjust the chassis height to its stored calibrated level.
I suppose you believe this because the level at the left-front corner is reading 113 mm when intuitively you'd expect to see a large negative value. But if this is the case you must understand that the level is derived by software running either in the ABC controller (likely, to me) or in your iCarsoft scanner. Further, I suppose the implausible 113 value could be a consequence of iCarsoft misreading a memory location from the ABC controller. Whatever, it seems to me the level sensor is not responsible for "113".
If this were my car the first thing I would do is use Star Diagnosis' to have ABC adjust the chassis height to its stored calibrated level.
05-28-2019, 04:49 PM
#3
Member
Thread Starter
Thank you for the response. You obviously know more about the ABC system than I do, so let's proceed on the basis that I don't understand it; that's pretty much so... I'm good with spanners - I can strip and rebuild an engine, and not have parts left over, and it will start... - but understanding electrical stuff is not my strong point.
The iCarsoft is the diagnostic tool I have; it's pretty useful, but limited compared to a Star, which I don't have.
I take your point about the reading of the LF sensor; the implausible reading is likely to be effect, not cause, then. I'll try jacking the car up to normal running height on that corner, and see what voltage readings I get.
Well, I jacked up the LF corner, and with it jacked up, took readings of sensor voltage, vehicle level, and plunger travel, in all three ride height positions. The results are attached; could I ask you to take a look at them?
The LF sensor readings never vary. You can see why I assumed that it might be a faulty sensor; it looks as though it's stuck - broken or detached link arm maybe? Could that perhaps still be the problem? If not, does anything now look particularly probable?
The problem with getting the car to my indie for a Star diagnosis is that I reckon I'd do some damage either driving it there, or even putting it on a recovery truck, as it is - there's very very little ground clearance on the LF corner.
Thank you again.
The iCarsoft is the diagnostic tool I have; it's pretty useful, but limited compared to a Star, which I don't have.
I take your point about the reading of the LF sensor; the implausible reading is likely to be effect, not cause, then. I'll try jacking the car up to normal running height on that corner, and see what voltage readings I get.
Well, I jacked up the LF corner, and with it jacked up, took readings of sensor voltage, vehicle level, and plunger travel, in all three ride height positions. The results are attached; could I ask you to take a look at them?
The LF sensor readings never vary. You can see why I assumed that it might be a faulty sensor; it looks as though it's stuck - broken or detached link arm maybe? Could that perhaps still be the problem? If not, does anything now look particularly probable?
The problem with getting the car to my indie for a Star diagnosis is that I reckon I'd do some damage either driving it there, or even putting it on a recovery truck, as it is - there's very very little ground clearance on the LF corner.
Thank you again.
Last edited by E55BOF; 05-28-2019 at 04:54 PM.
05-28-2019, 08:09 PM
#4
Banned
Prior to purchasing an iCarsoft of my own and learning its limitations, I believe I'm guilty of suggesting to members of the forums that it was a suitable alternative to Star Diagnosis. That isn't the case, as this thread shows.
Jacking up the car and taking readings was a terrific idea which provides some interesting data. However, it isn't enough to solve this puzzle, and it seems to suggest that more than one problem may be occurring.
When you jacked the car, naturally the left-front control arm had to move. But the level sensor voltage remained at 0.47 volts, and as you noted that could be a broken linkage or a faulty sensor. It could also be a faulty ABC controller input circuit or possibly even an iCarsoft reporting error.
When you cycled the ride height three struts reacted as one might expect. But the left front apparently to me did not react at all, as evidenced by no change in the "strut travel" and the vehicle level sensors. It seems to me a faulty ABC controller output circuit or front valve block must account for this. On the other hand, if the left front did in fact move, then two sensors are faulty, or iCarsoft is not reporting them accurately.
Then there's the issue of how a voltage of 0.47 gets translated to a vehicle level of 113 mm. The only explanation I have to offer is a software error in iCarsoft or the ABC controller, and both seem somewhat implausible to me. That said, it's important for me to emphasize that I am just a bloke on a car forum -- I'm not a professional auto technician -- and you should value my viewpoints accordingly.
Let's see if other forum members can make better sense of all this before I suggest further steps.
Jacking up the car and taking readings was a terrific idea which provides some interesting data. However, it isn't enough to solve this puzzle, and it seems to suggest that more than one problem may be occurring.
When you jacked the car, naturally the left-front control arm had to move. But the level sensor voltage remained at 0.47 volts, and as you noted that could be a broken linkage or a faulty sensor. It could also be a faulty ABC controller input circuit or possibly even an iCarsoft reporting error.
When you cycled the ride height three struts reacted as one might expect. But the left front apparently to me did not react at all, as evidenced by no change in the "strut travel" and the vehicle level sensors. It seems to me a faulty ABC controller output circuit or front valve block must account for this. On the other hand, if the left front did in fact move, then two sensors are faulty, or iCarsoft is not reporting them accurately.
Then there's the issue of how a voltage of 0.47 gets translated to a vehicle level of 113 mm. The only explanation I have to offer is a software error in iCarsoft or the ABC controller, and both seem somewhat implausible to me. That said, it's important for me to emphasize that I am just a bloke on a car forum -- I'm not a professional auto technician -- and you should value my viewpoints accordingly.
Let's see if other forum members can make better sense of all this before I suggest further steps.
Last edited by bobterry99; 05-28-2019 at 08:12 PM.
05-29-2019, 07:31 AM
#5
Member
Thread Starter
Eureka! FOUND IT!! The little bracket bolted to the suspension upper wishbone at that end of the sensor linkage has snapped off! I suspect from the look of the fracture that the ball joint had been very slowly seizing, getting stiffer and stiffer, and there was some rust there too, and eventually the bracket gave way.
The sensor electronics are perfectly serviceable - they're sending the (implausible) values they sense when the linkage is permanently in its lowest possible position, way outside the normal range of operation.
As I suspected, the linkage is indeed broken.
Looks like we were both right.
I'll fit a new sensor, and that should fix it. Unless I'm incredibly lucky and it's pretty close, then I'm off to my indie to set the suspension heights. I'll post when it's done.
The sensor electronics are perfectly serviceable - they're sending the (implausible) values they sense when the linkage is permanently in its lowest possible position, way outside the normal range of operation.
As I suspected, the linkage is indeed broken.
Looks like we were both right.
I'll fit a new sensor, and that should fix it. Unless I'm incredibly lucky and it's pretty close, then I'm off to my indie to set the suspension heights. I'll post when it's done.
05-29-2019, 09:58 AM
#6
Banned
From your description I'd presume you only need new linkage and the sensor is fine. It's quick and effortless to test the sensor with it separated from the linkage.
The sensor arm rotates through an angle of 70 degrees and outputs a proportional voltage in the range of .5 to 4.5 volts. That voltage can be viewed with your iCarsoft, of course.
It's still peculiar to me that a minimum voltage (.47) translates to 113 mm. It would be interesting to me to see how the chassis level reading changes as the voltage is swept through .5 to 4.5 volts by rotating the arm...
The sensor arm rotates through an angle of 70 degrees and outputs a proportional voltage in the range of .5 to 4.5 volts. That voltage can be viewed with your iCarsoft, of course.
It's still peculiar to me that a minimum voltage (.47) translates to 113 mm. It would be interesting to me to see how the chassis level reading changes as the voltage is swept through .5 to 4.5 volts by rotating the arm...
05-29-2019, 12:22 PM
#7
Member
Thread Starter
[QUOTE=bobterry99;7766664 It's still peculiar to me that a minimum voltage (.47) translates to 113 mm. .[/QUOTE]
Me too, but there it is. I can only assume it's so far beyond its normal travel limits that the voltage signal is God-knows-what, because it doesn't know...
The little linkage arm and bracket is still available, and does not come with the sensor, so I've ordered one; if that's really all it is, I've saved the cost of a Star session to set the suspension levels as well. If not, a new sensor will be next.
Fingers crossed....
Me too, but there it is. I can only assume it's so far beyond its normal travel limits that the voltage signal is God-knows-what, because it doesn't know...
The little linkage arm and bracket is still available, and does not come with the sensor, so I've ordered one; if that's really all it is, I've saved the cost of a Star session to set the suspension levels as well. If not, a new sensor will be next.
Fingers crossed....
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06-03-2019, 04:05 PM
#8
Member
Thread Starter
I managed to remove the sensor today - lower fixing nut seized and the stud sheared off! Damn!! I can't get a drill in there with any accuracy to try to drill it out; I can't even SEE it when the drill is in there. The upper stud is fine, so the only way I can see to secure the lower end is to drill a hole in the mounting plate (above the existing mounting hole) and the car inner wing, and keep it in place with a sheet metal screw. Does anybody have a better idea? Any sort of adhesive that would do the job?
I moved the sensor arm through its range of motion, and the voltage varies as I do it, so I guess the sensor is fine anyway.
I moved the sensor arm through its range of motion, and the voltage varies as I do it, so I guess the sensor is fine anyway.
06-04-2019, 03:04 PM
#9
Senior Member
I managed to remove the sensor today - lower fixing nut seized and the stud sheared off! Damn!! I can't get a drill in there with any accuracy to try to drill it out; I can't even SEE it when the drill is in there. The upper stud is fine, so the only way I can see to secure the lower end is to drill a hole in the mounting plate (above the existing mounting hole) and the car inner wing, and keep it in place with a sheet metal screw. Does anybody have a better idea? Any sort of adhesive that would do the job?
I moved the sensor arm through its range of motion, and the voltage varies as I do it, so I guess the sensor is fine anyway.
I moved the sensor arm through its range of motion, and the voltage varies as I do it, so I guess the sensor is fine anyway.
06-04-2019, 03:15 PM
#10
Member
Thread Starter
Replaced the linkage, bored a hole and secured the lower end of the mounting to the inner wing as described. It's fixed...
