Guys I just replaced the Hitachi compressor with the SAME Hitachi model compressor on my 2006 LR3 v6

part# K04L-L136-34SP
Miessler Automotive Air Suspension Compressor

I thought it would be a plug and play and instead its giving me code:

C1A36 = Exhaust Valve

I was told by local shop that the LR3 needs a software update by Dealer only ...
any thoughts?

closest dealer is over 1 hour away and the car is sitting high in the rear and low in the front with red susp. warning light on so I would have to get it towed! any suggestion on what to check or how to fix it?
Cheers

 

This is typical Land Rover.

There might be a problem with the new to you compressor however am I to assume your new compressor is brand new and not off a wrecked 3?

Also, why did you replace the compressor?

In other words, was replacing the compressor solving the wrong problem?

Regardless, I expect the good news is your new compressor is fine and that it is not now the problem.

Hence as you asked, yes, you have to start looking elsewhere.

The link below is to a number of files related to the air suspension system. I suggest you take the weekend and read up on the system so that you understand how it operates. Once you understand it, you will find it is really quite a simple system.

Regarding this business of software updates, one does not update the compressor as there is no printed circuit board or hard drive/memory chip within the compressor. Any updating physically occurs elsewhere. This is an example of why you will have to spend some time reading the files to get an understanding of where the problems and solutions may or may not be.

Yes, were you to have installed the newer not Hitachi compressor, the LR replacement AMK brand compressor, then yes, a software update would have to be done, but again, not to the compressor but because of the compressor.

When you starting reading the files, look for info on the compressor relay located in the engine compartment. As a general rule, when you install a replacement compressor, one also installs a new 70 amp relay, R7E.

This is primarily because a bad compressor tends to destroy the relay feeding power to the going bad compressor. Also check that you have power to the compressor both before and after you change out the relay. I presume that you seem to have volts to the new compressor but do not confuse that with having the required amps at the compressor. A new relay helps resolve that concern. I note the file in the link below related to the relay referenced now has over 3000 views - it is a the relay of concern.

DISCO3.CO.UK Photo Gallery - LR3 Air Suspension fuse 35P ECU Manual Shut Off Switch

 

This is a link to some more compressor files.

DISCO3.CO.UK Photo Gallery - Broken Air Compressor RQG500060

Below is a link to the whole album; I gather you are new to the 3.

As such, you will have to become the local expert in your area on your 3 so you can guide your independents around your 3 rather than thru your purse. The guys will actually appreciate your help as a 3 is not so much a 4x4 as an All Wheel Drive Computer.

DISCO3.CO.UK Photo Gallery - Home > Member Galleries > bbyer

 

bbyer, thats great information...very helpfull. Thank you!
Based on what Im reading if I was mechanically inclined I would definately check the rear Reservoir Valve block and Pressure Sensor: (car sits way up in back and low in front! n I think where noise comes from) and Control module. My confusion is from that code : C1A36 (exhaust valve) , the Hitachi compressor is brand new and exhaust valve is intact. I found a bulletin stating that when a new compressor is installed the C1A codes will appear and car needs to be reprogrammed. I want to check the wires at this point but dont have the tools to take the inside metal side boards under the plastic ones off and really inspect the harness. Codes before this all ordeal were (C1A20 - pressure too low.. and C1A27 - compressor circuit) so I started by replacing the compressor and new relay (gray) and thought it would be a done deal...
Those codes were gone but new ones appeared : U0421-94, B1A00-46 and C1A13-64 with a very loud compressor noise coming from the back (compressor noise but not it) the shop was able to clear them by recalibrating the module but now the C1A36 is permanent and noise still there...Why ???? would the scan tool tell if a wire is disconnected or other components were not working??
Im going to disconnect the battery overnight and check the connection/wires inside the front wheel wells today and if nothing changes Im afraid the Dealer is my only choice at this point...

 

You are to be complemented at changing out the old relay when installing a new compressor as there is now one less problem to be concerned with.

From what I can gather, as the rear end is high, your compressor must be making air plus the wiring and rear block valve is also OK and I suppose the block valve located near the compressor is also fine as air is at least getting to the rear block valve. If so, then air must also be getting to the front block valve but not thru it.

This is because the front air springs remain low and hence that suggests the the front block valve will not let air thru it. Rather than it being a block valve problem however, it may be the wiring to the front block valve is not sending signals to the three solenoids within the block valve. Well actually, power may be getting to one of the solenoids, (the one that allows air to flow left to right and vice versa, but not the other two that allow air into the respective air springs.

This then suggests that the front wiring harness must be looked at. The link below relates to a typical failure location of the front wiring harness located in the area behind the left front black plastic wheel well liner.

Before you remove the liner however, look into both the left and right wheel wells towards the rear, at the visible portion of the wiring harness leading to the wheel height sensors.

To do this, first turn the steering full left and look in the right front wheel well at the rear; then the same with the steering full right. What you are looking for is possible cutting/damage to the wheel height sensor harness due to rubbing of the rubber tread portion of the tyre on the harness. This can occur when the there is near full suspension travel and the steering is hard over one direction or the other and if the harness is not secured tightly to the frame. If the problem was there, it is an easy fix - just repair the conductors.

As you asked, a general comment regarding codes is that there is no code for a broken, cut, or corroded wire or connector.

As such, the computers tend to invent codes in an attempt to explain the problem. The net result is that one can be looking at the wrong end of the vehicle for a problem.

As to the compressor noise you spoke of, a broken aluminum mounting bracket or missing rubber cushion can cause alot of noise but a software fix would not normally then quiet things down. A broken or cracked bracket I think would have been noted when the compressor was changed out however. If for some reason, there is something the compressor is vibrating against, that would also make a noise.

As to software upgrades for the Hitachi, back in 2006, Land Rover did a general fleet wide software upgrade in an attempt to fix a whole number of problems, some of them related to the air suspension. As all the 3's were then under factory warranty, most of them received the upgrades.

Then around 2008, there was another software fix released for the Hitachi which was to be loaded along with a new Hitachi compressor - that is probably the upgrade you have been referring to. The upgrade was only done with a compressor replacement and was not fleet wide as LR charged for it.

As to what this upgrade did, LR was rather silent, but it appears that the shut off pressure of the compressor was reduced perhaps 20 psig. This was so the new compressor did not have to work as hard at the end of the fill cycle. Yes, the compressor did have to work more often as less pressure meant less air for the springs, but overall, there was thought to be less stress on the compressor and that would improve it longevity.

Whether or not your 3 has that software fix does not really matter however to the operation or not, of a replacement compressor. It is a nice to have thing, but not a must have.

I trust I am making some sense; that is your new compressor is OK and the problem is probably within the wiring harness to the front. If so, that is not easy to determine either.

DISCO3.CO.UK - View topic - Suspension fault, front cross-link valve (SOLVED)

 

Those are some awesome pictures ..Thank you! ..I was able to locate the exact same wires/plugs and NOTHING seams to be out of order nor split ......dirty but not damaged. Im having the Lr3 towed to Dealer on Thursday ..in the mean time my quest continues
Thank you so much for your help bbyer .. looks like you've been of great help in the past I see.
I really appreciate your time in helping me as well.

 

QUESTION: bbyer, in reference to the Hitachi upgrade by LR, do you know if the "new" Hitachi compressor had the same wire connection as the AMK?
Reason Im asking is the first compressor I purchased hoping to replace the exact one on my LR3 had a different 4 prong plug instead of a 6 prong...so I returned it since the susp. fault didnt go away and received an Hitachi with a 6 prongs plug hoping to do a plug a play thing.
My question is Will the update from LR work on either one of them? or does it have to be a specific one to receive the upgrade?
here's some pics with explanations for you:

1st new Miessler Hitachi received n returned:



my original Hitachi compressor with the 6 prongs plug:


right now a new Hitachi compressor with the same 6 prong plug is installed on my Lr3 ..and I have the same susp. fault message

 

What you ask is really interesting.

First off, I did not know know about there being two different plugs; that is one with four pins and another with six pins.

You might phone Miessler and ask them just what vehicle the four plug compressor was for. I think you are on to something here. I see on the tag in the jpg, the word SPORT and Discovery 3/4 rather than LR3. It also seems to me that one could have a 6 conductor connector wired to 4 conductor compressor as they all look the same. This is the sort of quality control problem second source suppliers have.

Attached is a wiring diagram pdf that I have. I suggest you print off the one sheet pdf.

In the top right corner you will see a box named Air supply unit (D252). That is the air compressor and both connectors. The outline box shows eight conductors leading to the compressor.

C0780-1 and C0780-2 are the thicker power supply conductors, the supply and the ground that are located in the separate two conductor connector.

In the six pin connector of interest are located the other six conductors, C0781-1/2/3/4/5/6 related to the exhaust valve and two temperature sensors.

I note in your jpg where you show the returned 4 conductor plug, that there are four conductors leading into the 4 conductor plug plug, not six.

Re the 6 conductor connector plug on your new compressor, can you look at it again and see if there are four or six conductors leading to that plug?

Note on the wiring drawing that the exhaust valve connector pins are -1 and -4. If for some odd reason, are only four conductors leading to the new six conductor plug, then my guess is perhaps pins 1 and 4 are not connected. This would be really odd however; it would be more reasonable that one of the temperature sensors was deemed not required.

C0781-1 shows as a BW colour wire and C0781-4 shows as a BU colour wire. Black is usually Black, W is White, and U, Blue so the temperature sensor wires may be Black with White or Blue stripes, or some mix of that.

The system could fill without an exhaust valve and there is a mechanical relief valve but with the exhaust valve not electrically connected, there would be some sort of error code thrown. It would be rare that a displayed error code is a code that directly relates to the real problem.

In other words, missing two conductors would be too simple, but I do wonder.

We will all be interested in what your dealer finds to be the problem. I find that often the tow job is more expensive than the fix, hence it would be nice to figure out the solution locally.

 

I agree ...very confusing and to add...both the two Hitachi compressors (4 prongs and 6 prongs) have the same part # .
I will call the company tomorrow and ask..but I have the feeling I wont get the answer Im looking for.
..per your request, I opened the cover and looked at the plug on the last Hitachi installed and it has the 6 prongs all wired and connected to the harness plug just like the original one.
...I guess we'll see what the Dealer comes up with...I'll keep you posted.

 

Perhaps remove the yellow 60 amp fusible link in the engine compartment fuse box and test it for continuity. F10E is the yellow rectangle nearest the battery tie down bolt in the jpg below.

I assume it is OK as I do not think much would operate but from reading a Disco3 thread, the fusable link turned out to be defective.

Other than that, I am pretty much out of ideas.

Yes, what the dealer finds will be interesting.

Also I presume no one has uploaded the new AMK software update into your 3?

While the AMK will operate seemingly OK with the Hitachi software, it does not work the other way around. Apparently you get exhaust valve error codes - I just wondered?