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PDCC faults.

deMort

Well-known member
Joined
21 Mar 2015
Messages
11,244
Ive now got my second Cayenne in with a PDCC fault ..

They are intermittent .. a split second basically but amber then red warning lights until you cycle the ignition .

Both of the faults i have seen .. and bearing in mind this is new as i've never seen it before are due to a pressure problem with the rear roll bar .

First fault a couple of months back .. fault code for under and over pressure readings from the pressure sensors and intermittent .. code will always be passive if the car is not moving so codes can be cleared ..

test plan .. very complicated but it lists just about every part of the system from pump to rear roll bar .

First car . it was an educated guess to be honest .. RA pressure sensor fault .. x2 sensors in the rear valve body .. i kinda figured this was the most obvious fault .. no way i could prove it without replacing it .

Intermittent fault .. so not much i can test as the fault only happens for a split second when driving and at a certain angle whilst cornering ..

I changed the rear valve body .. ok big issue .. the pipes were all corroded .. i had to cut them all out and replace .. we are into sensible money here for a fault i cant prove until its replaced .

In this case it fixed the fault .

I now have a second car with RA pressure too low .. im leaning towards the same fix but as above its different codes and no real test plan .. wing and a prayer again .

Ok so my point .. im of the opinion that its old fluid and the sensors are blocking .. these seem to be the same as the brake sensor on the master cyl that often packs up .. debris gets in and blocks it .

I feel .. although no proof at all that a replacement PDCC reservoir which will replace most of the fluid might be the way forward .. its a hunch .. educated but a hunch none the less ..

if you have the fault then this wont help .. i tried it .

Change the reservoir which is actually a service item and change the fluid .. basically removing the reservoir will replace most of the fluid as there's no drain or bleed on these .

An FYI for you guys basically .
 
Thanks Iain!

Great info, funnily enough, my 'Chassis System Faulty' warning is back. It seems to happen as soon as I go over 5mph

This warning appeared consistently for 2-3 days, then disappeared for nearly 2 weeks but now it pops back up after moving off

I am yet to find the fault code as yet, my normal OBD reader doesn't work and I bought a dodgy PIWIS wire but durametric v3 and v5 doesn't seem to support the 2008 cayenne. So I need to get it in somewhere.

I am planning to change my PDCC bottle, only £40 or so. Also, one of my rear lines was replaced approx a year ago, so I'm going to assume the fluid is fairly fresh and clean. My PDCC pump does make a whurring noise, Rennlist forum seems to suggest this is normal with age, I am wondering if my pump was run dry when the line burst. Eitherway, I'm used to the noise now and the radio hides it.

I willlllllllllll get the code read and report back in my progress thread.

Iain, when you refer to replacing the valve body, what is that exactly? The bit round bit on the rear ARB?

:worship:
:thumb:

P.S, With the PDCC not working, my GTS is not so enjoyable to drive! It has really highlighted what it is capable of! I now have to hold myself up when cornering! :pc: :nooo:
 
This is a bit of a new fault on me .. i've fixed one and am awaiting authority to continue with the second one .. but because i saw two i posted this thread as it got me a little worried .. is this going to become common .

Your Gen .. i think it was a chassis fault message , you need to get fault codes of your car to continue .. perhaps a garage to read them out .

The gen i have on the go gives a PDCC failure message but its 2011 model so different cluster and warnings .


Fault codes are RA pressure too low / too high .. this refers to the rear valve body .. or the pump .. or the roll bar .. or pretty much every part of the dam system .. thanks for being so specific Porsche .. sigh.

My theory is its the rear valve block , n/s /r on the axle and covered by a black plastic cover with x2 10 mm bolts .. image below .

Pressure sensors and solenoids in this item and the fault is due to this .

it may not be though it can be other things and dependant on the code i can nail it down a bit .

Downside .. this ain't cheap .. the pipes corrode in .. valve body plus x4 pipes .. = expensive .

I did an awful lot of searching to find this image i can tell you .

get me a fault code and i can go from there .

BTW .. when the car sees a fault it disconnects the roll bars .. probably not the best driving experience but it will reset after an ignition on / off .

Both my cars had this fault after about 4 miles of driving and on a corner .. 44 degrees of steering angle on the last one in comfort mode .

Sports mode and it will be different .. its higher speed and cornering .


BTW .. your pump noise now makes sense .. a pump with no fluid can get damaged .. PAS pumps on sports cars .. common for this to happen .. pump might be your problem .. but i need a code to confirm .
 

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Perfect! I actually went and looked through all the files you send me to find more out on the valve body!

I reakon I've got moisture in a plug or something from all of the jet washing I've been doing under the car, behind the arch liners etc.

I willllllllllll get the code read!! I need to, will save me pulling each and every plug on the valve body out and back in.

I actually quietened the PDCC pump after getting some WD behind the pulley, soon went back it's normal volume..

I am trying to hunt for a second hand PDCC pump to pull it apart and see the internals and see if I can find an answer for everyone's loud pumps! It must be able to get rebuilt!
 
Can't seem to find anything for 15629, this was 100% the code.
I can find info on 15627 and 8 but that's all.

The guy who did it does all Ferrari stuff, he said check the wiring/plugs as a start. It definitely said rear block or a block in rear something or other.

Fluid is probably just over a year old after the rear high pressure line was changed. I will assume that the error never occured for the previous owner, I have done approx 700 fault free miles before the error popped up which is now consistently occuring.
 
The code i don't know but RA i do .. its the same fault i've had / got on the two i have had .. the second one i'm still waiting to fix .

Best guess atm .. its the Rear Axle ( RA ) valve body that's at fault .. downside to this .. the pipes corrode .. i had to cut and replace 3 out of 4 of them on the first one , this one and it looks like 4 .

I changed the reservoir and fluid as part of the job last time but if yours has been done then no point ..

be aware the fault can also indicate a fault with the roll bar itself .. it wasn't on my last one but i have literally done this fault once with another on the go ..

Perhaps leave it for a week or so and give me a chance to play with the next one .


i need to dig out some fault codes and check them to see what else it could be ..

Time limited tonight but i've made a note .. investigation ( me ) and see where to go .
 
Cheers Iain!

I bloody wish I paid more attention to the error code description, google isn't showing anything for 15629! I replied on the code thinking I will find info easily but I can't find a single mention of it ANYWHERE!

The unit itself and valves/sensors is all pretty simple in essence. I would love to undo the pressure sensors to see if they can be cleaned out, the valves too, I can't justify £700 for what may be the failing of a small and quite basic component which could easily be serviced... I might see if I can get a second hand one to pull apart to investigate. I have spent a fair while googling and it seems a lot of the US guys bleed the system by driving it due to not having the equipment, air is just driven out at the bottle end, not sure on that, I did have pre conceived ideas that it would be like bleeding brakes and someone would need to be watching the fluid out of the nipples while the car flexs the arms. I won't go so far as to self bleed anyway.

I'll wait to see what you find with the car you've got, I'll check the wiring and give things a light tap to see if I can magic things back to life for now. I am just hating the way the car drives without PDCC!!

:thumb:
 
To bleed the system you need a tester .. it basically rolls the car from side to side .. there are no nipples etc you undo .

You can check the wiring plugs for corrosion on the RA valve body .. i did .. but neither of them is that problem .

it .. to me is a solenoid or pressure sensor fault in that unit .. removal though .. well i'm afraid i replace the unit as i can't do that sort of repair .

A fault code for yours is essential though .. there are many fault codes listed for these and a code is needed to point us in the right direction
 
About to go and get under the car...

interestingly, found these pressure sensors.

Want to see if I can locate a part number on the ones fitted to the valve body...

61v3c2H4L2L._SX425_.jpg
 
I have the list of codes for 2010 onwards .. so not your model and it doesn't list that code im afraid . .. to be honest i would like to put a tester on it and see what the codes are .

The pressure sensors you have shown .. they look similar but On the Porsche parts list they are not a separate item .. its the entire valve body .. RA . or nothing .

we are still guessing though .. we .. I ... need an actual fault code referring to the problem that i can understand ..

we have an open day coming up for 911 UK only ... if possible i can put a tester on it then .. watch the meets forum as its in June .

My second one is going nowhere atm .. Customer ... selling garage and warranty all fighting so its sitting in the corner unloved for now .
 
Ahh, it is odd, nothing gives any results for the code.

I will need to get it down to you! Even if I book it in through the books, it's pissing me off!

I did some poking around last night, I found 1 plug with rust at the pins, gave a clean but no joy once buttoned back up.

I've got a new fluid tank but I think I will refrain from fitting it until I work out what the issue is as if it results in changing a pressure sender or something, it's going to dump the fluid.

Just for reference of anyone not willing to change the entire valve block, I have found replacement pressure senders.

Pic of sender on my car

32819255067_5527b884ee_c.jpg


Pic of sender which is available new.

81CG17Dl6mL._SL1500_.jpg


There was a thread I saw yesterday, where a guy undone the bleed nipples while car was running and got air out of the system, I didn't think air could get trapped as it is a circuit system I believe with fluid cycled back through the bottle but according to him, he got air out..

555x417x000002421879_3.jpg.pagespeed.ic.FWGJSGlK5d.jpg


ARB body showing the nips... Can't say I want to fiddle with those as they'll probably snap.

I will await further diagnostics..
 
if its possible to change those pressure sensors then my money is on them being the problem and i can tell you why ...

early cayennes had a problem with brake pressure sensors .. the same as what these seem to be.. fitted upside down .. dirt can collect in them and interfere with the operation .. these seem to be the same and fitted the same .

Porsche doesn't list them as a separate unit so its the valve body at £700 nicka :eek:

I had to " blanket change the body as no separate parts available " pipes were done as they were corroded .. i couldn't get them undone .

Air in this system has to come from a leak .

i didn't bleed the last one after changing the RA valve body .. i used the tester to operate it and that bleed it .

Basically though .. we need an accurate fault code to continue .. weather via me or a garage local to you .. we need to know what the car thinks is wrong.

Best guess from me anyways and considering ive only done one PDCC fault so far i'm a little short on experience :(
 
Cheers Demort, I pulled the sensors for a clean while doing a fluid change, wanted to poke around. No change after giving them a blast with WD but going to order a new pair as not costly.

I think it's probably best for me to change those for the sake of it and then I'll be in touch. A diag and computer bleed would be good.
 

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