Suspension driving me nuts!!!

Hi all, new to the forum. Ive read countless threads but cant seem to get to the bottom of this issue im having.

So i started to get christmas lights on the dash, dsc, epb, hdc and suspension faults, then the car goes into limp mode. I have a icarsoft iid tool and i get a lot of codes but most are communication faults but i also got some suspension faults.

When leaving the car for a few days the suspension doesnt drop so i dont think there are any leaks at the struts, but when i checked for air leaks i noticed bubbles coming out from the blue and red hoses at the conpressor, so i changed the compressor and this resolved that issue but still the car goes into limp mode. Ive also checked the lines and the reservoir for leaks but couldnt come up with anything.
With the iid the codes im getting are
C1A09 - pressure sensor signal
C1A08 - pressure sensor supply
C1A13 - pressure does not decrease when venting gallery
C1131 - air supply
C1A20 - pressure increase too slowly when filling reservoir

now ive also checked the gallery pressure on start up and it goes to about 1780kpa and then drops to about 250kpa immediately after the compressor shuts off. Now what happens is the compressor will keep cycling even with the car stationary and it will get to a point that it doesnt reach 1780kpa because i believe the compressor is shuting down because it gets too hot. Im really at my wits end with this suspension issue.
Any help would be greatly appreciated
Costa

Hi, you should have focused yourself on the pressure sensor and it's circuit after the leak was fixed cos that's what the first codes are about, what modell of Disco though?

Hi and thank you for the reply
Its an 08 tdv6 diesel
Is there a way of testing the pressure switch to find out if its faulty or would it be a case lf swapping it for a new one?

I dont know a simple way to test it, anyway for more info about troubleshooting see the attachment even though the codes you've got are not 100% as in the LR protocol

Thanks for that, i will have a good look over the troubleshooting file you’ve sent over. I might just replace the pressure sensor aswell and see if this helps

After more hours on the disco I’m still not having any joy. I replaced the pressure sensor and found one of the air lines was a bit clogged so I replaced that and also rebuilt all the valve blocks. I’m really at a loss at what to look for next, the codes I’m picking up now are

diesel v6
P0402- exhaust gas recirculating flow excessive detected
The egr’s have been capped off so doubt it’s this

auto gearbox
U2023- fault received from external node

abs
U0401- invalid data received from engine control module/power train control module

Instrument pack
U0132- lost communication with ride level control module

hvac
B1b74- front foot defrost mode stepper actuator
B1b75- front foot face mode stepper actuator
B1b76- front left air blend stepper actuator
B1b77- front right air blend stepper actuator
B1b78- system pressure
There’s codes are always present so doubt it’s anything to do with these

parking brake controls module
U0100- lost communication with engine control module/ power train control module

all terrain control module
U0402- invalid data received from transmission control module
u0416- invalid data received from vehicle dynamics control module

Ride level control module
U0416- invalid data received from vehicle dynamics control module

Body control module
B1d06- left turn signal circuit
B1d14- interior lamps 2 circuit

I though the issue was caused from a suspension fault but now I don’t think that is the case, any ideas of what to look at next?

Post 07 you need emulators or a map to stop the egr faults showing, a physical blank on its own is not enough.

Have you checked the large wiring loom plug under the rear of the battery? bit of an arse to get to but they get wet and corrode.

Lot of comms faults there, have you googled any of them?

I haven’t checked the wiring under the battery, I will do this on my next day off. I have googled all the codes but with regards to the comms fault nothing specific comes up, I don’t want to be chasing my tail to find out that I’m not even looking in the right place. It’s just I’ve spent soo much time on this issue and don’t seem to getting any closer to resolving the problem

Costa-p said:

I haven’t checked the wiring under the battery, I will do this on my next day off. I have googled all the codes but with regards to the comms fault nothing specific comes up, I don’t want to be chasing my tail to find out that I’m not even looking in the right place. It’s just I’ve spent soo much time on this issue and don’t seem to getting any closer to resolving the problem

Click to expand...

If you do some googling you can find all the wiring diagrams for a discovery three and discovery four model
If you cannot find them ask Gary a.k.a. @gstuart on here and I am sure he will send them to you

Costa-p said:

I haven’t checked the wiring under the battery, I will do this on my next day off. I have googled all the codes but with regards to the comms fault nothing specific comes up, I don’t want to be chasing my tail to find out that I’m not even looking in the right place. It’s just I’ve spent soo much time on this issue and don’t seem to getting any closer to resolving the problem

Click to expand...

hi @Costa-p

sorry to hear ur wiring issue, certainly understand it can be frustrating but there’s plenty of us here that can help

would u be so kind to test the canbus to see what comes back , disconnect ur battery and with a multimeter test the cabin OBD2 socket plse

One test probe to pin 6 other test probe to pin 14, read ohms

one test lead to pin 3 other test probe to pin 11, read ohms

as @lynall mentioned have a look at the TCM and ECM behind the battery as indeed they can suffer with ingress of water which can cause the terminals to corrode

also noticed that u have the left turn signal error, plse ensure all ur lights and brake lights are working 100% as even a bad brake light switch can cause issues , can ignore U codes

along with ensuring ur battery is in tip top condition , with the engine off should read a minimum of 12.6 Vdc

here’s a wiring diagram for u

https://onedrive.live.com/?authkey=!AGC0h_ifAw7UTqs&id=4BC2D89C85C7C171!5831&cid=4BC2D89C85C7C171

lastly the wiring connectors for ur suspension compressor with be behind ur passenger side headlight

Plse a let us know what those ohms readings are as that will help us identify if u have issues in ur canbus as that tests every single module within the vehicle , so always best to do that first before having to delve deeper into individual ones

whats the latest with ur suspension plse, the figures u gave is correct , as indeed after it shuts off it will release the excess air with that usual hiss, of course shouldnt cycle on and off so there’s a leak somewhere , the reservoir tank is a common place where they leak on top of the weld which is situated on top where u cant see it , can pull the pipe off the reservoir valve block for the tank , then attaching either a vacuum or pressure gauge, that saves u having to remove it , u can also use a vacuum gauge/ pump to ensure all ur valve blocks are sealing correctly , but see how u get on with the canbus test first, then the connections behind the front passenger side headlight , then battery voltage with the engine off, lastly all ur lights etc and see what results findings

finally what diagnostics are u using plse , thks

Hope that helps a little getting u started

gstuart said:

hi @Costa-p

sorry to hear ur wiring issue, certainly understand it can be frustrating but there’s plenty of us here that can help

would u be so kind to test the canbus to see what comes back , disconnect ur battery and with a multimeter test the cabin OBD2 socket plse

One test probe to pin 6 other test probe to pin 14, read ohms

one test lead to pin 3 other test probe to pin 11, read ohms

as @lynall mentioned have a look at the TCM and ECM behind the battery as indeed they can suffer with ingress of water which can cause the terminals to corrode

also noticed that u have the left turn signal error, plse ensure all ur lights and brake lights are working 100% as even a bad brake light switch can cause issues , can ignore U codes

along with ensuring ur battery is in tip top condition , with the engine off should read a minimum of 12.6 Vdc

here’s a wiring diagram for u

https://onedrive.live.com/?authkey=!AGC0h_ifAw7UTqs&id=4BC2D89C85C7C171!5831&cid=4BC2D89C85C7C171

lastly the wiring connectors for ur suspension compressor with be behind ur passenger side headlight

Plse a let us know what those ohms readings are as that will help us identify if u have issues in ur canbus as that tests every single module within the vehicle , so always best to do that first before having to delve deeper into individual ones

whats the latest with ur suspension plse, the figures u gave is correct , as indeed after it shuts off it will release the excess air with that usual hiss, of course shouldnt cycle on and off so there’s a leak somewhere , the reservoir tank is a common place where they leak on top of the weld which is situated on top where u cant see it , can pull the pipe off the reservoir valve block for the tank , then attaching either a vacuum or pressure gauge, that saves u having to remove it , u can also use a vacuum gauge/ pump to ensure all ur valve blocks are sealing correctly , but see how u get on with the canbus test first, then the connections behind the front passenger side headlight , then battery voltage with the engine off, lastly all ur lights etc and see what results findings

finally what diagnostics are u using plse , thks

Hope that helps a little getting u started

Click to expand...

thank you very much for all this info. I will test it all on my day off and will report back the values i get. As far as the suspension goes, i believe thats all sorted, i dont appear to have any leaks and it seems to be working as it should. Im using a icarsoft iid tool.

Costa-p said:

thank you very much for all this info. I will test it all on my day off and will report back the values i get. As far as the suspension goes, i believe thats all sorted, i dont appear to have any leaks and it seems to be working as it should. Im using a icarsoft iid tool.

Click to expand...

ur so very welcome , great the suspension is behaving it’s self

Fingers crossed u find out the issue , thks and indeed plse let us know how u get on

gstuart said:

hi @Costa-p

sorry to hear ur wiring issue, certainly understand it can be frustrating but there’s plenty of us here that can help

would u be so kind to test the canbus to see what comes back , disconnect ur battery and with a multimeter test the cabin OBD2 socket plse

One test probe to pin 6 other test probe to pin 14, read ohms

one test lead to pin 3 other test probe to pin 11, read ohms

as @lynall mentioned have a look at the TCM and ECM behind the battery as indeed they can suffer with ingress of water which can cause the terminals to corrode

also noticed that u have the left turn signal error, plse ensure all ur lights and brake lights are working 100% as even a bad brake light switch can cause issues , can ignore U codes

along with ensuring ur battery is in tip top condition , with the engine off should read a minimum of 12.6 Vdc

here’s a wiring diagram for u

https://onedrive.live.com/?authkey=!AGC0h_ifAw7UTqs&id=4BC2D89C85C7C171!5831&cid=4BC2D89C85C7C171

lastly the wiring connectors for ur suspension compressor with be behind ur passenger side headlight

Plse a let us know what those ohms readings are as that will help us identify if u have issues in ur canbus as that tests every single module within the vehicle , so always best to do that first before having to delve deeper into individual ones

whats the latest with ur suspension plse, the figures u gave is correct , as indeed after it shuts off it will release the excess air with that usual hiss, of course shouldnt cycle on and off so there’s a leak somewhere , the reservoir tank is a common place where they leak on top of the weld which is situated on top where u cant see it , can pull the pipe off the reservoir valve block for the tank , then attaching either a vacuum or pressure gauge, that saves u having to remove it , u can also use a vacuum gauge/ pump to ensure all ur valve blocks are sealing correctly , but see how u get on with the canbus test first, then the connections behind the front passenger side headlight , then battery voltage with the engine off, lastly all ur lights etc and see what results findings

finally what diagnostics are u using plse , thks

Hope that helps a little getting u started

Click to expand...

So I’ve had some time today to look at the car.
Battery voltage with engine off was 12.45V
Battery voltage with engine running was 14.12V

I also checked the Ohms for the OBD2 port
Pin 6 & 14 was 59.8 Ohms
Pin 3 & 11 was 61.8 Ohms

Do these figures look about right

Costa-p said:

So I’ve had some time today to look at the car.
Battery voltage with engine off was 12.45V
Battery voltage with engine running was 14.12V

I also checked the Ohms for the OBD2 port
Pin 6 & 14 was 59.8 Ohms
Pin 3 & 11 was 61.8 Ohms

Do these figures look about right

Click to expand...

many thks for the data and indeed look ok apart from the battery , needs a good full charge overnight as u want to see a min of 12.6 Vdc with the engine off, if it’s over 4-5 x years old is worth changing , personally fitted a larger yuasa 019 instead of the 017 from Halfords , won’t buy offline again as then u have the hassle trying to return it if there are issues

so next thing , would u be so kind to measure ur suspension plse , in normal ride height , measure in MM from the bottom of ur wheel arch to the centre of ur wheels , can use some masking tape on the centre caps to aid u getting the suspension heights

then with diagnostics live data , wheel dead straight see what the degrees are plse

then ensure all ur lights, brake lights etc are all functioning plse

hope that’s useful to u as we can then progress further as required , oh and before I forget did u get the software patch added for ur EGR blanking plse as that will keep throwing up errors

plse let us know how ur get on

Almost forgot , may I plse add I assume you’ve had ur oil pump replaced with the upgraded one, including the timing belts ,