Suspension Fault - C1A18-64

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Mwood1164

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Just for those who be misled and waste money on a compressor. Unless of course the factory compressor comes with the valves. A bad compressor can not set this code. It is either the reservoir valve right there attached to the compressor or some other was being done and the line to the reservoir is pinched.
Your dealer lied to you my friend. They probably cleaned the valve just like the other poster posted. If something your being told doesn't make sense to you from the stealer then they are probably lying. Who cares though right you got your truck back fixed right?
 

f1racer328

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Happy Thanksgiving from my Disco!

I’ve been gifted this code. I’m going to pull apart the valve block near the reservoir and clean/inspect and go from there.

Drove around this morning, went to the gym, and it threw the code in the parking lot during startup. Like others here I haven’t off roaded in a while.

2013 with 123k miles.
 

ryanjl

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Just for those who be misled and waste money on a compressor. Unless of course the factory compressor comes with the valves. A bad compressor can not set this code. It is either the reservoir valve right there attached to the compressor or some other was being done and the line to the reservoir is pinched.
Your dealer lied to you my friend. They probably cleaned the valve just like the other poster posted. If something your being told doesn't make sense to you from the stealer then they are probably lying. Who cares though right you got your truck back fixed right?

I know this response is older than dirt and this poster was a one-pump chump, but I can assure you, after having gone through my entire suspension in the years following this, it was a the compressor that was replaced and nothing else. Nothing misleading here. I'd tell @Mwood1164 to buzz off, but it appears he left as quick as he came.

Not saying that's the only possible solution, but it was for me.
 

f1racer328

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I know this response is older than dirt and this poster was a one-pump chump, but I can assure you, after having gone through my entire suspension in the years following this, it was a the compressor that was replaced and nothing else. Nothing misleading here. I'd tell @Mwood1164 to buzz off, but it appears he left as quick as he came.

Not saying that's the only possible solution, but it was for me.
Yeah I believe you.

Since it was the $0 option, I pulled apart the valve block that sits right in front of the compressor and cleaned it. It wasn’t that dirty, but one of the O rings was a little sticky. The smaller o ring to be specific.

The fault is gone for now but my air suspension seems to raise on the slower side still. I’m thinking the compressor is a little weak, just like your dealer was stating.

Going to drive it for a week or two and see if the fault comes back. I have an off road trip planned for next month so I’d like to fix this beforehand.
 

ryanjl

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If it is your compressor, the cheapest place for a new one is LR Centre in the UK.
 

f1racer328

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So cleaning the center valve block didn't fix the problem. When I used my GAP tool to deflate the reservoir, basically nothing happened. I could hear a valve open up, but nothing came out. Removing the air line that goes to the tank also proved that it was basically empty.

It appears that the compressor isn't able to add air to the reservoir, when raising the suspension height the compressor runs constantly and seems to bypass the reservoir. The pressure increasing too rapidly makes sense, as it attempts to add air to the reservoir, and the pressure basically hits a limit right away and shuts the compressor off.

I've done some reading, and there isn't much information on it but there allegedly is a solenoid on the AMK compressors part # LR075760 that might be the issue. I called my dealership and they can get the part for $34, which is a lot cheaper than the online prices, however the claim it doesn't fit my vin (2013).

Not sure what to do. I'm tempted to take the compressor off and see if it has that part on it. I need to do a little more reading on how the air suspension works before I throw parts at this.
 

f1racer328

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Diagram.png
Diagram Desc.png


Alright, so looking at this diagram I'm pretty sure my problem is the center valve block.

Air goes into a common galley, and then can go a couple different directions.

After the air dryer/exhaust valve, it can go into the reservoir, the front valve block, or the rear valve block.

Air makes it into the front/rear valve blocks just fine, so I don't see a problem with the compressor itself. This is assuming the compressor isn't weak and can't push air into the reservoir, but who knows.

I'm going to probably replace the center valve block and go from there. Not sure if there is a way to test that valve blocks operation, either on my work bench or with the IID tool.


Update: Did some further diagnosing. I connected my tool, and monitored the gallery pressure, reservoir valve current, and reservoir valve percentage open.

When I start the car (no suspension fault) the vehicle applies current to the reservoir valve, it shows open (100%) for a moment, the compressor turns on, pressure starts rapidly building up (because it can't get into the reservoir) and then it faults and shuts off. I'm convinced it is a bad center valve block.
 
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f1racer328

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Alright, sorry for the triple post, but the problem is resolved.

It was the center valve block, the one that sits directly in front of the air compressor.

I took it off my car again today, applied 12 volts to the 2 pin connector and could hear the solenoid actuating, so I figured it was able to let air into the reservoir. I also had a suspicion that it was working because when I disconnected the line that goes from the valve block to the air reservoir, a fair amount of air came out.

I took it apart after testing it, and decided to take off the pressure sensor. The pressure sensors O rings were covered in desiccant material, and the threads were dirty. I cleaned the threads and o ring, blasted it all out with compressed air, and threw it all back together. I believe the pressure sensor possibly had some material inside of it, and it was causing an erroneous reading.

Everything is working as it should now. Car adjusts the suspension height, then opens the reservoir valve to fill the air reservoir to about 250 PSI. The height changes at its normal speed now, and the suspension fault is gone.

For anyone reading in the future, I had the pressure increases too rapidly fault. Not the pressure fills too slowly fault, which can be found on other threads.
 

f1racer328

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@f1racer328 , Where did you get that attachment!? I’ve been looking for similar technical resources.

Cheers.
If you search workshop manual or service manual on this site you should find a few.

https://drive.google.com/file/d/1B0jdD-ebSWTXU1t337RpMg-eTrc-ogdd/view - I think this is for a 2014+

https://www.mediafire.com/folder/5mhvubw2bens1/Dis4 - And this is for 2010-2013

Most of the stuff between the two vehicles is the same though. Even a lot of the LR3 information is good on our LR4s.
 

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