Self Leveling Suspension

[fmugur]

I got my faulty sensor identified by a indy shop using Autologic. Carsoft does not read the EHM module and I couldn't figure out on my own how to do it. So, I replaced my faulty sensor and after 2 min of driving the error was gone.
I was looking for a procedure to identify the faulty sensor without the need of a GT1 or these specialized tools. Here is what I found, too late for me but it might help some of you that try to diagnose the self level inactive problems.

Quote:
Originally Posted by Kurt Leman
Originally Posted by Kurt Lehman on the bmwe34m5 yahoo group

"RE: [M5] Help ... "Suspn Leveling" warning ...


Let me de-mystify the SLS sensor for you. Despite all the info to the contrary, it's just a switch. In typical German fashion, a fancy switch with non-contact sensing (so it has an easy-to-define "on" band, and won't wear out under constant high-frequency suspension motions), but it's still just a switch output (technically an open-collector transistor switch output.)

The operation is very simple: Centered, the output is grounded. Too high or
too low (spec'd as suspension height +/- 10mm) and the output is open, pulled "high" (near 12V) by the instrument cluster input. You can easily check this circuit and sensor operation as follows:

1. The sensor passes through a 21-pin connector next to the battery under the rear seat. This is an easy place to probe. Looking at the back of the
connector where the wires coming out of the rear floor enter the connector, the 3 wires in the center row of pins on one end are the sensor wires, pins 12, 13, and 14. Pin 12 (three from the end of the middle row) is a black wire with brown stripe and yellow dashes -- this is the sensor output. The next pin (13) is the ground, and the end wire in the middle row (14) is +12V power. You can easily probe with a DVM in the back of the connector.

2. Turn the key to the first "on" position. You should see 11-12V on pin 12
with respect to ground, and 0V on pin 14.

3. Turn key one more click to the "run" position.
STOCK: With car at nominal height, you should now see ~0V on pin 12 (~.35V) and +12V on pin 14.

LOWERED: If your car is lowered you will see voltage on pin 12 still. -A/E

4. STOCK: Jack up the right rear of the car, and at some large height, the output on pin 12 will rise suddenly to near 12V again.

LOWERED: Jack up the differential carefully by an inch or two to simulate "stock" ride height, you will notice that the voltage on 12 has now dropped to ~0V. -A/E

5. STOCK: Lowering the jack should bring pin 12 back "low". If you load the car enough, you can trip the sensor to "high" state again. You can also undo the one 10mm bolt holding the sensor on (leave linkage attached) and turn the sensor to see the above readings.

LOWERED: Lowering the jack will cause pin 12 to go back high again. -A/E


6. Cars with no SLS simply ground pin 12 to defeat the warning. You can do the same thing if you want to ignore the message if your sensor is bad and you don't want to replace it, or if your car is lowered with an SLS delete kit. You can simply place a jumper wire between the wires leading to pins 12 and 13.-A/E



http://www.unitedbimmer.com/forums/e...el-delete.html

[blueagle]

Latest update........

I have parked my X for 3 nights to check if rear air suspension of left rear side will hold at normal height........result is FAILED !!!!

Problem of left rear side is till collapasing after several days in the garage...Indie shop cannot resolve problem...Once you unlock the door the height goes back up to normal ....well, I have to live with it until you guys can give me some possible solutions...

[balongbalong]

Originally Posted by blueagle

Latest update........

I have parked my X for 3 nights to check if rear air suspension of left rear side will hold at normal height........result is FAILED !!!!

Problem of left rear side is till collapasing after several days in the garage...Indie shop cannot resolve problem...Once you unlock the door the height goes back up to normal ....well, I have to live with it until you guys can give me some possible solutions...

definitely a leak in the system. either lines from compressor to the air spring or the new air spring was not installed properly or it wasn't new at all.

[mysweetx5]

Originally Posted by blueagle

Latest update........

I have parked my X for 3 nights to check if rear air suspension of left rear side will hold at normal height........result is FAILED !!!!

Problem of left rear side is till collapasing after several days in the garage...Indie shop cannot resolve problem...Once you unlock the door the height goes back up to normal ....well, I have to live with it until you guys can give me some possible solutions...

I'M EXPERIENCING THE SAME ISSUE TOO, AND AS SOON I START THE CAR, YOU CAN NOTICE AND FEEL THE REAR VEHICLE LIFTING BACK-UP TO NORMAL POSITION SLIGHTLY. BUT HONESTLY! IT DIDN'T BATTER ME TO MUCH AS LONG AS THE REAR GETS BACK TO IT'S NORMAL HEIGHTS.

FOR ME, IT SEEMS LIKE A BEGINNING OF FAILLURE OR (A TIRED PART) THAT START TO RAN OUT FROM THE SUSPENSION LEVEL SYSTEM.

[01 X5 4.4i E53/M62 ENGINE TYPE [/BLUE COLOR].

[balongbalong]

Originally Posted by mysweetx5

I'M EXPERIENCING THE SAME ISSUE TOO, AND AS SOON I START THE CAR, YOU CAN NOTICE AND FEEL THE REAR VEHICLE LIFTING BACK-UP TO NORMAL POSITION SLIGHTLY. BUT HONESTLY! IT DIDN'T BATTER ME TO MUCH AS LONG AS THE REAR GETS BACK TO IT'S NORMAL HEIGHTS.

FOR ME, IT SEEMS LIKE A BEGINNING OF FAILLURE OR (A TIRED PART) THAT START TO RAN OUT FROM THE SUSPENSION LEVEL SYSTEM.

[01 X5 4.4i E53/M62 ENGINE TYPE [/BLUE COLOR].

if its a leak in the system, the compressor will keep on running to maintain the height of the vehicle, that will lead to a premature failure on your compressor. that's automatically more money if you need to replace the compressor

[TwinsPoppa]

Originally Posted by blueagle

Latest update........

I have parked my X for 3 nights to check if rear air suspension of left rear side will hold at normal height........result is FAILED !!!!

Problem of left rear side is till collapasing after several days in the garage...Indie shop cannot resolve problem...Once you unlock the door the height goes back up to normal ....well, I have to live with it until you guys can give me some possible solutions...

Hi blueagle,

If you're still having problems with the rear suspension, maybe some of what I experienced may help.

I recently had my left side (both front and rear) go down but not always. The front more so than the rear. Ended up being a leaky front air strut. I replaced both since I'm almost to 60K miles. I had also taken care of other front suspension problems so that it did not make sense to me to not replace both fronts. On the rear, they said they checked all the other three and seemed to hold pressure so they felt that I had no leaks.

Afterward initial replacement of the front struts, I had two issues. One was the X was not level and the other was the left rear still went down sometimes. I think it happened twice in a span of a week.

All four corners were at different heights (differences being from 1/8" to 1/2"). However, weasel said it's common to have slight differences. The shop I use don't have a GT1 and are not experienced with it. So, they allowed me to adjust the ride height in the shop since the X was sitting on its tires. Afterwards, they let me have it for a week to make sure things were all okay. When I returned to the shop for wheel alignment they adjusted the sensors (by adjusting the holder height) to get it even. They did it without telling me prior and I just left it as is.

Later when I got it home, I decided to play around with the GT1 and found some things I had heard about but never investigated further prior. One was you can set the suspension "zero point" through Control Module Functions. This is basically setting the default ride level height.

I had done a write-up about ride level adjustment through Service Functions using the GT1 but now I realize that my understanding of it was incomplete. That way is you measure the existing ride height at each wheel and the GT1 compensates compared to the zero point setting. What I discovered in the Control Module Functions is actually setting the zero point. Basically you adjust the ride height to what you want then push a button to remember that as your default ride height.

The other things I found under Control Module Functions was you can adjust independently the ride heights incrementally up or down. The complete front axle or the rear axle can also be adjusted incrementally at a push of a button. The exact dimension for each increment I don't have yet but its about 3/16" to 1/4".

I experimented with my default ride height (zero point) being lower than stock (as before for me) and higher than stock (like when you adjust for more clearance). I wanted to see if I could feel the handling differences. I currently have it higher than stock because I just haven't had time to play around some more. Probably I'll adjust it lower than stock again but higher than my prior setting.

Since that time, I have not had the rear left go down at all. As a matter of fact, since after the shop adjusted the sensors, I have not had the left rear go down.

I don't know, what if anything, resolved the left rear from going down. I'm just relaying my experience and maybe your shop can glean something. Maybe try setting your default ride height to higher or lower temporarily and see if that changes your results. Maybe adjusting the sensor heights ...

Good luck and would definitely be interested in your findings.

[DrumAdrian]

Hi TwinsPoppa,

What is this GT1 and how to I get one to adjust my ride height?

Also, I am having this "pump it up" in the morning issue but I haven't had time to really troubleshoot it lately. Also, did they just adjust the position of the sensor to adjust ride height? I didn't know this was possible.

Awesome post dude. Thanks for sharing all that info.

Adrian

[TwinsPoppa]

Originally Posted by DrumAdrian

Hi TwinsPoppa,

What is this GT1 and how to I get one to adjust my ride height?

Also, I am having this "pump it up" in the morning issue but I haven't had time to really troubleshoot it lately. Also, did they just adjust the position of the sensor to adjust ride height? I didn't know this was possible.

Awesome post dude. Thanks for sharing all that info.

Adrian

Hi Adrian,

GT1 is a system, consisting of hardware & software, used by BMW dealerships to diagnose, code/program the vehicles. This system is being phased out or has already been by BMW.

Some people/companies sell online and through ebay what I refer to as "laptop GT1". This is basically the GT1 software running on a laptop instead of the proprietary GT1 hardware. They cloned the system but it does not have 100% functionality of the original. For example, I don't think it supports all the different attachments like the original GT1 (like test probes or doesn't support wireless attachments).

Here's a link to some of mine and others experience:
http://www.xoutpost.com/bmw-sav-foru...aptop-gt1.html

Cost varies but its around $700 - $1000 for the complete system. The actual cost of the GT1 that the dealers use I heard run in the tens of thousands originally.

The value of these latop GT1s can be realized more by actual mechanics who will put the effort into learning the system. For myself, its enough for me to know its just a hobby.

Yes, they adjusted the sensor height to level the X. They did it as an un-asked favor, as at the time I didn't know how to use the GT1 to make the incremental adjustments, and they thought I'd want them to do it. I didn't find out until after they did it. Actually, I preferred they didn't do that. I was fairly confident there was a way using the GT1 but, at the time, didn't know exactly how.

I don't believe that its a big deal or that it may lead to problems. So, I didn't make them re-adjust. They were just trying to help me out free of charge. Bottom line, though, is the proper way to adjust ride height level is through the use of a GT1 or some equivalent - not adjusting the sensors themselves.

If you end up getting a laptop GT1, look at the link and search here and on the web. Lots of info. and will try to answer your questions as best as I can. Good luck!

[DrumAdrian]

Thanks,

I've seen those before but I didn't remember it by the name GT1. I bought a hacked version of carsoft and i use that for checking out certain things on the car.

I think the price of the real software is ridiculous and the eBay version is a deal in comparison.....but still pricey.

I think I may just have it checked if I bring my X5 to the dealer for something later. I get the feeling that my A.C. compressor is going out or maybe I'm just low on refrigerant. I hear a sound when I turn on the AC so i need to check it out. I just really really don't like going to the dealer. Those smug little customer service reps are annoying and separate me from my car and the knowledgeable tech working on it. That's all I care about. The car and the drive, NOT the coffee and muffins in the waiting area.

Thanks again dude,

Adrian

[TwinsPoppa]

Originally Posted by DrumAdrian

Thanks,

I've seen those before but I didn't remember it by the name GT1. I bought a hacked version of carsoft and i use that for checking out certain things on the car.

I think the price of the real software is ridiculous and the eBay version is a deal in comparison.....but still pricey.

I think I may just have it checked if I bring my X5 to the dealer for something later. I get the feeling that my A.C. compressor is going out or maybe I'm just low on refrigerant. I hear a sound when I turn on the AC so i need to check it out. I just really really don't like going to the dealer. Those smug little customer service reps are annoying and separate me from my car and the knowledgeable tech working on it. That's all I care about. The car and the drive, NOT the coffee and muffins in the waiting area.

Thanks again dude,

Adrian

On the sound from the A/C, might want to search about replacing the First Stage Resistor or something like that. Plenty of threads on that and might be worth a quick search.

Cya around .. Jose