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Discussion Starter · #1 ·
Sorry this is long, but I've been at this a while, trying to benefit from all the previous posts before posting myself.

I have a 2005 LR3 SE with 157,000 miles. I have had the air suspension fixed twice. The last time I asked for the old compressor. In the summer I begin having intermittent suspension faults, so I just kept it at normal height. It went away for a couple of months. When it came back it was no longer intermittent. I purchased a Faultmate FCR and read the following codes:

C1A18 Pressure increases too rapid when filling reservoir
C1A27 Compressor circuit - circuit short to ground or open
C1131 Air Spring Air Supply Unable to pressurize gallery
U0416 Invalid data received from vehicle dynamics control module
C1A20 Pressure increases too slow when filling reservoir
C1130 Air spring air supply

My ride had been getting lower and lower, so I tried clearing the codes and restarting to see if I could get some air back in the bags. Only one code returned, C1A27, but it shuts down the specials and gives the "suspension fault normal height only message."

I decided to try rebuilding my compressor, so I did two things. First, I removed the compressor (nightmare reaching the top bolt) and ordered replacement kits. Second, I took apart the old compressor (for practice) and cleaned it up; filtered the dust from the drier; and put it back together. I hooked it to the battery for a simple bench test that I saw on the x8r rebuild youtube, and I could not stop the airflow with my thumb. I put my poor man's refurbished compressor in but there was no change. I still had C1A27.

I rebuilt the compressor that I pulled out using:
jpo500010 valve, springs, o-rings
ywb500220 relay
A drier/piston rebuild kit from x8r ltd

Before rebuilding, the compressor did not pass the "thumb test." I could hold my thumb over the hole and stop the air from coming out. After rebuilding I could not prevent the airflow. So I re-installed it. Same code C1A27.

I thought perhaps the aftermarket relay was bad so I replaced it with one from land rover dealer parts department. No change.

I then tested all the wires from the compressor to the Air Suspension Unit under the dash. I had continuity on all, and no apparent shorts (i.e., no continuity between wires).

Frustrated, I reasoned that since the original faults involved both the reservoir filling to rapidly and filling too slowly, that perhaps the issue was the pressure sensor on the reservoir valve block. So I replaced the whole block.

Before trying again, I checked the continuity of the wires to the new valve block. I also checked the other wires in more depth. I noted that when the ASU plugs are in, there is continuity between the wire from pin 7 on C2030 (motor temperature sensor ground) and the wire from pin 17 on C2321 (compressor temperature sensor ground). I figure that makes sense, cause both are grounds. Also, in the other direction, when the compressor is plugged in and I test on the ASU side, there is continuity between pin 5 and 6 on C2320 (exhaust valve negative, and exhaust valve positive). I figure when the compressor is plugged in they just complete a circuit? (I'm not an electrician).

So I plugged everything back in and turned on the truck. This time, I received two codes:

C1A36 Exhaust Valve - general electrical failure - intermittent
C1A27 Compressor Circuit - circuit short to ground or open - permanent

I haven't checked all of the other circuitry because there were no faults to the front or rear sensors or valve blocks. I looked at the front valve block connector and it looked clean. I looked at the three connectors inside the left wheel-well. They look old, but I was afraid to try disconnecting and testing them for fear of breaking wires in the process.

Could there be a short in the compressor even though it runs on the bench when connected to battery. Is there a way to test for that?

Could C1A27 be caused from somewhere else?

Any thoughts on why C1A36 would show up after I replaced the reservoir valve block?

Any help would be greatly appreciated.
 

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Discussion Starter · #2 ·
Solved!

Often the simplest explanation is the correct one. Since fault C1A27 states that there is either a short to ground, or an open circuit, it would seem (especially on a circuit that has 3 fuses and a relay) that one of the fuses was causing an open circuit. I checked and rechecked all of the fuses and replaced the relay (twice).

Somehow, however, I missed the F10 fusible link. I replaced that (for $1.83) and I'm operational again.

The C1A36 fault that showed up after replacing the reservoir valve block was probably caused by all of my probing around to check the circuits.

So in the end the rebuilt compressor does work, so thank you to all of the previous posts that explain how to do it.
 

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Thanks for the update.

We appreciate hearing the solution as well as the problem.

It seems you have a good knowledge of the system, and now even better.

Thank you.
 

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how to interpet a code

I was rereading the first post and then looking at the wording of the error code. I would not have figured out the problem, or if I did, it would have taken a long time.

The error code reads as below:

C1A27 Compressor Circuit - circuit short to ground or open - permanent

and means the circuit has either a:

short to ground

or the

circuit is open

and

is a constant error, (not intermittent), and therefore not one that comes and goes.

It would appear that I will have to be spend more time thinking about the error code wording that I am reading to understand its complete meaning.

It would have taken me forever to find the failed fusible link as they "never" go.
 
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