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  #1  
Old 01-18-2018, 04:44 PM
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Fixing your Air Suspension.

Folks

I write this purely in the hope that it will help others. I have spent way too much time, money & tears trying to fix my "Self Leveling Suspension Inactive" issue on my e53 4.8is. Being a 4.8is it has the EHCII or Twin Axle air suspension.

Things to keep in mind when trying to diagnose and fix your suspension once it starts displaying the message "Self Leveling Suspension Inactive"

This message will 'normally' remove all power to the actual compressor ensuring that it will not operate by using the ride height button. This is important to understand as I see many in the forums who spend time and money trying to get power to the compressor, replacing fuses, relays and even the compressor.

This is a "safety" feature, to protect you and the car. The easy way to test this is to use a diagnostic scanner that can read EHC errors and clear them! Once the error is cleared the suspension will start to operate until the error returns, which could be seconds, days, weeks or even months.

With the error cleared you should now be able to start diagnosing.

There are five probable areas that can cause the system to fail. Spending time looking at these will help you and save you money. A good Scanner/Diagnostic Tool is really a must but not always an essential.

1) Air Bags: One in each corner. If they leak? The car will sag in that corner(s) This may take time to become visible. Park the car on level ground and leave as long as you can (the longer the better) if it sags in one corner? You have a leak in that corner and need to replace the bag.


2) Compressor: These units get tired as they age. They are designed to keep the reservoir topped up by running briefly for a few seconds in any one time. They are not designed to for long runs. If you have a leak. The compressor attempts to keep the system inflated and burns out. Fixing the leak is crucial. Then buy a rebuild kit from www.bagpipingandy.com The kit costs a fraction of the price of a new compressor and is relatively easy to install using a 1/4 drive socket set, screwdriver and some torx bits. Rebuild time around 1 hour. The kit consists of a new piston ring, seals, bolts etc and (best of all) colour, detailed instructions. You can also buy a new cylinder bore and drier refurb kit if you want to rebuild the whole unit (I did) and it is worth every penny. This way you are only doing the job once.


3) ECU: For this you really do need a good scanner that will interrogate the ECU in depth. These rarely fail and are very expensive to replace. If your compressor is lifting and lowering the car, it is unlikely that the ECU is at fault.


4) Reservoir/Connectors: These do fail. A spray with diluted washing up liquid should show any bubbles as leaks. It is not unheard of to damage the connectors by removing the spare wheel. These are all speedfit connections and easily replaced.

5) Ride Height Sensors: These are known to fail and relatively cheap to replace
They can be read using inpa or a good scanner. They can also be seen to have broken, normally after the car has been lifted on a jack or ramp??


Other things to consider:

The compressor has a heat sensor that will kill the power, if it kicks in. The sensor detects heat caused by continual running. It can be seen operating using inpa or other good scanners. Remember!! If the compressor is continually running or, running for longer than a couple of minutes you most likely have a leak.


In my own mission to repair my compressor. I found that the drier was badly rusted (they will all collect moisture that is their job) but the pepper pot holes were blocked by rust restricting air flow. Some of the rust had been drawn into the cylinder bore, scoring the piston ring and bore. This allows air to escape and reduces pressure while extending running time.

All these parts were available from www.bagpipingandy.com and delivered in a couple of days along with a complete set of springs, bolts etc.

The bottom line is that the compressors get old and tired and do need a refurbish. It is a cost and time saving task that works instantly.

Lastly.

Andy (bagpingandy) has been a huge help to me as I struggled through diagnosing and repairing my system. Had I simply bought and installed his kit I would have saved weeks of pain and a large amount of cash. It is very easy to get carried away trying to fix what is staring us in the face. Andy's help, time and effort made a world of difference to me and is all encapsulated in his full colour instructions that come with each kit.

I am not associated with Andy he has not asked me to wrote this. I am an avid enthusiast who believes that good work deserves good recognition.

Have fun.

Bruce
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  #2  
Old 01-18-2018, 05:16 PM
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I finally connected to my EHC somehow the physical connection was breakng. Relocated the module and plugged it in pumped right up. Now just need to replace driver rear sensor.
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  #3  
Old 01-19-2018, 03:54 PM
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Quote:
Originally Posted by brucemillar View Post
Folks

I write this purely in the hope that it will help others. I have spent way too much time, money & tears trying to fix my "Self Leveling Suspension Inactive" issue on my e53 4.8is. Being a 4.8is it has the EHCII or Twin Axle air suspension.

Things to keep in mind when trying to diagnose and fix your suspension once it starts displaying the message "Self Leveling Suspension Inactive"

This message will 'normally' remove all power to the actual compressor ensuring that it will not operate by using the ride height button. This is important to understand as I see many in the forums who spend time and money trying to get power to the compressor, replacing fuses, relays and even the compressor.

This is a "safety" feature, to protect you and the car. The easy way to test this is to use a diagnostic scanner that can read EHC errors and clear them! Once the error is cleared the suspension will start to operate until the error returns, which could be seconds, days, weeks or even months.

With the error cleared you should now be able to start diagnosing.

There are five probable areas that can cause the system to fail. Spending time looking at these will help you and save you money. A good Scanner/Diagnostic Tool is really a must but not always an essential.

1) Air Bags: One in each corner. If they leak? The car will sag in that corner(s) This may take time to become visible. Park the car on level ground and leave as long as you can (the longer the better) if it sags in one corner? You have a leak in that corner and need to replace the bag.


2) Compressor: These units get tired as they age. They are designed to keep the reservoir topped up by running briefly for a few seconds in any one time. They are not designed to for long runs. If you have a leak. The compressor attempts to keep the system inflated and burns out. Fixing the leak is crucial. Then buy a rebuild kit from www.bagpipingandy.com The kit costs a fraction of the price of a new compressor and is relatively easy to install using a 1/4 drive socket set, screwdriver and some torx bits. Rebuild time around 1 hour. The kit consists of a new piston ring, seals, bolts etc and (best of all) colour, detailed instructions. You can also buy a new cylinder bore and drier refurb kit if you want to rebuild the whole unit (I did) and it is worth every penny. This way you are only doing the job once.


3) ECU: For this you really do need a good scanner that will interrogate the ECU in depth. These rarely fail and are very expensive to replace. If your compressor is lifting and lowering the car, it is unlikely that the ECU is at fault.


4) Reservoir/Connectors: These do fail. A spray with diluted washing up liquid should show any bubbles as leaks. It is not unheard of to damage the connectors by removing the spare wheel. These are all speedfit connections and easily replaced.

5) Ride Height Sensors: These are known to fail and relatively cheap to replace
They can be read using inpa or a good scanner. They can also be seen to have broken, normally after the car has been lifted on a jack or ramp??


Other things to consider:

The compressor has a heat sensor that will kill the power, if it kicks in. The sensor detects heat caused by continual running. It can be seen operating using inpa or other good scanners. Remember!! If the compressor is continually running or, running for longer than a couple of minutes you most likely have a leak.


In my own mission to repair my compressor. I found that the drier was badly rusted (they will all collect moisture that is their job) but the pepper pot holes were blocked by rust restricting air flow. Some of the rust had been drawn into the cylinder bore, scoring the piston ring and bore. This allows air to escape and reduces pressure while extending running time.

All these parts were available from www.bagpipingandy.com and delivered in a couple of days along with a complete set of springs, bolts etc.

The bottom line is that the compressors get old and tired and do need a refurbish. It is a cost and time saving task that works instantly.

Lastly.

Andy (bagpingandy) has been a huge help to me as I struggled through diagnosing and repairing my system. Had I simply bought and installed his kit I would have saved weeks of pain and a large amount of cash. It is very easy to get carried away trying to fix what is staring us in the face. Andy's help, time and effort made a world of difference to me and is all encapsulated in his full colour instructions that come with each kit.

I am not associated with Andy he has not asked me to wrote this. I am an avid enthusiast who believes that good work deserves good recognition.

Have fun.

Bruce




Here we see the damage to the ring, bore and rusty drier all replaced now from bagpipingandy.com



Sent from my iPhone using Tapatalk
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  #4  
Old 03-27-2018, 09:51 AM
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Thanks for the info. Mine (05 4.4L) has the 'inactive' light on. Compressor pumps on its own at what seems like a normal cycle (meaning doesn't go on every 5 minutes), no sagging at any of the wheels, no sound of losing air from the wheel wells after pump cycle, BUT>>> the so-called passenger-side front Zenon light sensor arm was broken when I got the truck. I have replaced it last week. Wondering if the ECU uses info from that sensor to self-level or auto-detect issues? Can someone help please.
Thanks in advance.
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  #5  
Old 03-27-2018, 10:02 AM
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It is entirely possible that it does use the headlight leveling sensor? I do not know for sure?

Once you have the 'Inactive' message come on, you may have to clear it using a code reader/scanner AFTER you have carried out any work. My icarsoft will clear suspension errors as will 'inpa'

When you refer to a "normal cycle" I am unsure what that is in terms of time? YOU really need something like 'inpa' to be able to see what the system is doing. That will show you if it is running to long/hot, slow etc.

The most common problem is the compressor piston ring fails (wears out) due to the system over running in an attempt to compensate for a loss of pressure (leak). People then fix the leak, but do not re-build the piston, which is now doomed to failure.

It is a neoprene/plastic ring so does not take too much to wear it out.

What I can tell you is this. On my 4.8, I thought the system was working as designed, until I rebuilt the compressor. Boy did that make a difference. The car raises & lowers in a couple of seconds. Prior to the rebuild that was around a minute.

I also note that with it rebuilt, it hardly runs when the car is being driven. Prior to that it would run for a few seconds at almost every stop light etc.

Good luck.
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  #6  
Old 03-27-2018, 10:26 AM
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Ok, thanks. Mine doesn't run often, I hardly hear it and my level is constant. I'm almost sure that I have a sensor problem. Anyways, I'll keep digging. Thanks

Last edited by Rockabilly Rebel; 04-01-2018 at 02:44 PM.
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  #7  
Old 10-05-2018, 09:55 AM
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And here i have to share a video when i changed my piston compressor Oring from my 4.8is

https://youtu.be/zUyA86eHz40
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  #8  
Old 10-05-2018, 10:15 AM
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This is a GREAT post! However I will say the ECU/module can have errors and need to be switched as it was superseded a twice in the E53 vehicles equipped with EHCII production - If your problems are not fixed by compressor rebuild, there are no leaks, the bags are all fresh and holding air, and the level sensors are good and the small ball-socket linkages are not seized, and still getting random errors or gremlins, I would look into whether the module is original or not - Mine had to be replaced before I got the vehicle.


I will contact Andy about the "full rebuild" kit as the last time I went to lower the vehicle with the switch you're correct it almost took a minute to do so.



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Old 10-05-2018, 10:21 AM
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How much was the "full rebuild" kit you bought? Which looks to be something not listed on his website but I will email him for information - If I'm going to rebuild I'd rather do it once and completely, and is it easy with no special tools?
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Old 10-05-2018, 12:56 PM
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Great thread! I've been dealing with the dreaded sag in my rear drivers side for a little over a year now. Sometimes it wont sag for days other times in just a few hours or over night.

It sounds like the best way to troubleshoot a bag vs the sensor would be to jack up that corner, remove wheel, support the axle on a jack stand (to get some pressure on the bag) and spray some soapy foam water?
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