Disco 3 (LR3) Rear Air Suspension Raising & Lowering, Valve % Mismatch

Hello everyone! I'm dealing with an issue on my 2007 LR3 Discovery 3 (L319) air suspension.

I was driving home yesterday and got a red air suspension fault and went down to the bump stops. I don't have pictures of this. I thought I took them, but I guess not, but the code reader showed issues on 3 of the 4 sensors. This was c1a74-1c and I believe the rear right, and one of the fronts, but again I don't have the exact codes. I cleared them to try and get home, which basically worked but I had to keep clearing the code every mile or so for ~2 miles, and I intermittently saw a message about the suspension raising slowly.

I left the car in the driveway, with the fuses removed ( was still level in the morning, so I think this precludes the rear valve block? ), and started it again this morning and drove it around a mile or so ( was trying to stay close to home in the event something went bad ) and haven't had the fault again *yet*, so I can't pull up the other codes.

However, I did notice when I got out of the car that the compressor was running and the rear was basically rising, then lowering and repeating. The front didn't move. To be more specific, I left the engine running, and it wasn't when I got out of the car as the stopped the air suspension as I believe is to be expected, but when I shut the door, I saw the rear start raising.

Here is a video of what I'm describing ( Rear left tire ):
youtube . com/watch?v=hRqOA0dVn0k


I have a video from the opposite corner ( Rear right tire ):
youtube . com/watch?v=xXEPU2kz5u0


Here is a video of the code reader while this was going on:
youtube . com/watch?v=iSN4-j_TKQI

What I thought was abnormal about this is that you'll see when raising, the rear left tire valve percentage open is 0%, and the rear right tire valve percentage is 100%, then when briefly deflating, they reverse and the rear left becomes 100% and the rear right becomes 0%.

I say abnormal because when manually moving the suspension up and down on the vehicle, the front behaves in what I *think* would be the expected manner:
youtube . com/watch?v=lwvMZPUuhX8 .

The first 45 seconds or so is me setting up and moving the vehicle up to the off road position from access, and both valve percentages are 100%. Then you'll hear 2 clicks as I lower it down to access mode, and they both open again at 100%, and both go to 0% when the position is reached. I'm presuming this is the correct function, and the rear is not behaving like it should?

If that's the case, what is this a symptom of?

Possibly related, though I'm not 100% sure as I thought I saw similar values when the air suspension was working as intended. I'm curious if these voltages are as expected. The sensor supply voltage is the expected 5V line, but the sensor voltage is ~2V, is that expected? IE is there some resistor or something purposely lowering the voltage to ~2V as that is what the sensors themselves need?

Check all the level valves are still connected, either physically or see if the readings change as you adjust the suspension.

lynall said:

Check all the level valves are still connected, either physically or see if the readings change as you adjust the suspension.

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Thank you for the prompt reply. The valves are all connected. Not sure what you mean by "see if the reading change as you adjust the suspension", are you referring to the readings that are in the video(s) I supplied links for or something else?

conrad10781 said:

Thank you for the prompt reply. The valves are all connected. Not sure what you mean by "see if the reading change as you adjust the suspension", are you referring to the readings that are in the video(s) I supplied links for or something else?

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Video links are not links, and I am to lazy to copy and paste!
I meant readings on a diagnostic tool.

Gary aka @gstuart will be the man for this, he has a real fetish for air susp faults, give him an hour or two and he will advise you in more detail.

lynall said:

Video links are not links, and I am to lazy to copy and paste!
I meant readings on a diagnostic tool.

Gary aka @gstuart will be the man for this, he has a real fetish for air susp faults, give him an hour or two and he will advise you in more detail.

Click to expand...

Okay, thanks. I tried putting the links so they were just links but they didn't show up in the post. They have the readings from the diagnostic tool.

Slow to raise is an over worked pump usually caused by a leaking air tank.

biketeacherdave said:

Slow to raise is an over worked pump usually caused by a leaking air tank.

Click to expand...

Thank you. There doesn't appear to be a leak, but instead the pump is overworked by the rear constantly raising to what appears to be the vehicle lifting passed a defined point, then releasing, and repeating constantly.

conrad10781 said:

Thank you. There doesn't appear to be a leak, but instead the pump is overworked by the rear constantly raising to what appears to be the vehicle lifting passed a defined point, then releasing, and repeating constantly.

Click to expand...

Coming back to the ride height sensor again, you need live data otherwise you will just end up down a rabbit hole.
Not uncommon for the loom right next to the sensor to fail, so common you can get short loom repair kits.

If you are keeping the car I can highly recomend the Gap IID tool.

sounds like its hunting for level maybe a loss of signal If you have no air leaks, check all relevant electrical wiring/ connectors and spray clean, self levelling is normal on park up, a good diagnostic tool is the key, but its sometimes the simplest thing @gstuart is the person to ask on D3 technical stuff

Hi

Plus 1 ^^^

indeed it looks like the height sensors are getting interrupted from the ECU , alas urs is the 4.4 V8 as just saw ur thread as well over on the D3 forum , put the link here as it includes the utube videos

https://www.disco3.co.uk/forum/rear...valve-mismatch-204406.html?highlight=c1a74-1c

alas was difficult trying to read the screens , might be easier as u scroll through to take a screenshot as ur also have a record

rear connector that goes to the rear height sensors is ref C0391 , U might want to start checking each height sensor in turn, ie , the arm hasn’t come off , or connector is bad , easily checked with a multimeter , once resolved it may req re calibration

there’s also 3 x connectors behind the front headlight , sorry can’t remember which headlight

indeed as mentioned the air tank could be leaking , normally on the top where the weld is, sadly if the compressor is over worked can simply burn itself out

if u don’t mind me saying , just go through it step by step in small chunks , otherwise ur drive urself nuts trying to pinpoint errors, lol, plus plse don’t ever get under the landy without axle stands

hope that also helps u

https://media.disco3.co.uk/gallery/albums/userpics/15405/Land Rover factory D3 air suspension description.pdf

The connector that then goes to both rear height sensors are C0391/ C0377, seen where a wire can break or bad connection

lynall said:

Video links are not links, and I am to lazy to copy and paste!
I meant readings on a diagnostic tool.

Gary aka @gstuart will be the man for this, he has a real fetish for air susp faults, give him an hour or two and he will advise you in more detail.

Click to expand...

tyregeezer said:

sounds like its hunting for level maybe a loss of signal If you have no air leaks, check all relevant electrical wiring/ connectors and spray clean, self levelling is normal on park up, a good diagnostic tool is the key, but its sometimes the simplest thing @gstuart is the person to ask on D3 technical stuff

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are u guys trying to say I’ve got an obsessions with air suspension, lol

seen this a couple of times where the car wouldn’t settle and indeed as you’ve mentioned with regards it hunting for a signal

Put the link in where the OP had posted over in the D3 forum as it shows the videos , looks like some of the height sensor supply Vdc was at zero , wondering if that back connector might be at fault

but indeed remember on mine it was like opening a massive rabbit hole as it was one thing after another , alas all down to previous owners who had bodged it to an inch of its life, lol

hope ur all keeping well

No its because you're the D3 genius mate, had similar issue cleaned all plugs, which are in some great places to catch dirt/moisture I always thought, couldn't tell you which one was at fault but resolved the issue

tyregeezer said:

No its because you're the D3 genius mate, had similar issue cleaned all plugs, which are in some great places to catch dirt/moisture I always thought, couldn't tell you which one was at fault but resolved the issue

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shucks ur make me blush, lmao , bless u for the compliment mate as means a lot , think it was just down to me having to rip my entire suspension apart that I learnt so much

really pleased u resolved the issue , always a team forum effort in how we all each have our own specialty so to speak, I look up to each and every one of u out of respect

thks again for the kind words

Hi @conrad10781

how u getting on plse as see u visited the site a day after all the above help was posted and wondering if there’s any update as always nice to know

many thks