Dave Waldo

This is the error alarm. It resets after each start up and comes back on after about 50 metres of driving and stays on until I stop.

957 turbo with PDCC and air suspension.
I wasn't going crazy but enough for traction control to be coming on occasionally. It was a windy 2nd, 3rd, 4th type road. I heard a couple of beeps then the alarm. The suspension looks to sit level but straight away the right rear feels like it has gone soft. Left rear and fronts feel ok but not pushing it to test it out. It's not bottom out soft just it just squats uncomfortably in the RHR on left hand turns and understeers.

The PSM switch doesn't stay on any more.

The adjustable suspension didn't work at first but now does.

Using the Durametric for the first time, I have error codes on most suspension files, were it says "Communications error, unable to connect to this module" but doesn't tell me which module.

However on the Vehicle Electrical systems file it says "Load signal generator terminal DF - Implausible signal, test conditions are not completed" with errors code 1117 part no. 7L.593.704.9A

In the Gateway file it says " PCM2" error code 459. Part no. 955.610.107.02

I have never used the Durametric before and I'm not sure how to turn this information into a fix. Do I just buy these part numbers and fit them. The car is new to me, I do have a Porsche service manual on order but it's not here yet.

TomF

First place to start is to check the fluid level in your reservoir. If you burst a PDCC hydraulic line, you may have run your pump dry. When I blew out a front PDCC line because the PO's Indy failed to properly secure the lines after an oil change, I got the same error and and the PASM went into limp mode. When mine blew, it was at about 75MPH in the midst of a very tight 270 degree offramp. I was able to hold my line and didn't lift off the throttle, but the difference in handling mid-turn was dramatic. It could have been a full on disaster and thank goodness my wife wasn't driving. I was able to pull right into a parking garage and was able to get the PASM working again after a couple of on and offs with the key. By that time, there was quite a bit of fluid coming from the line, but I didn't run the pump dry.

Start there and also inspect all your lines and the front and rear PDCC distribution blocks.

I am confident that someone more knowledgeable than me will chime in on the Durametric aspects of your dilemma.

Petza914

OP, based on your description of the condition in which the failure occurred and the symptoms, I think Tom's diagnosis is spot on. The original PDCC lines, though braided stainless, had no anti-abrasion coating on them, just the raw braids. They rub on stuff, wear through, then under high pressure situations like when you're pushing the car, one will burst. Porsche recognized this as an issue because when you go to buy replacement lines, you're going to notice that they're different now and covered in clear plastic like they should have been from the beginning. During my widebody build, I actually took my lines loose and used heat shink clear insulation to protect all my PDCC lines and make sure they were properly secured in the clamps and isolators.

Unfortunately, Durametric isn't as useful on the 957 generation Cayennes as it is on the previous generation as there are some modules it won't communicate with. For example with the Porsche PIWIS system you can access the stability control module and bleed the PDCC system which makes the car do a little dance as it forces fluid through the pumps and lines, but this option isn't possible with Durametric, even the Pro version I have. Eventually the system self-bleeds but that may be why you can't get good pinpointed failure data with the Durametric.

Here's the chart from Durametric that shows what functionality it does have in the 957 Generation Cayenne. To be able to bleed the PDCC system it would need to have a "Yes" under Activations for the Stability Control Module, which it does not. The Level Control Calibration note at the bottom applies to the air suspension, not the PDCC system.

Dave Waldo

Your both spot on. Thanks

It has blown a PDCC hose, it's an odd place to burst. I don't think the PO drove it hard so I wonder if the hoses aren't used to having to flex and overstressed that day.

No hoses in Australia, they have to come from the factory 2-3 weeks if the freight doesn't shut down from the virus.

Maybe get a mobile hose doctor in ??? Has anyone tried this ???

Dave Waldo

When the pressure drops does the pump stop or will it have run out of oil and seized ?

Petza914

Yep, that's what they look like when they fail. I don't think the pump stops when the pressure or fluid drop. It's odd the burst is on the underside of the hose and not the top side. I forgot to mention that the other thing I did when coating my hoses with plastic was to put wire totes around them on both sides of those rubber isolators so they can't move out of position.

While the system is empty of fluid you may want to order all new PDCC hoses and change them all to the new coated style if you plan to keep the vehicle for a while.

TomF

If it's been run dry for more than a few seconds, the tandem pump will need replacement. You might as well replace the reservoir at the same time as they are a service item at 40k intervals. Unfortunately, the pump is not cheap, IIRC. I'm glad you got the issue identified and hope you are back on the road soon!

Cheers!

Dave Waldo

If the power steering is still working as normal does that mean the PDCC pump is ok.

TomF

I don't think so. The pump is set up in tandem configuration and one or both sides can fail if they run out of fluid. Did the PDCC reservoir run dry? I would assume so if you kept driving it, which is totally understandable. One doesn't think of a Chassis Failure warning to be something catastrophic to components like the dreaded flashing check engine light, which means "shut off engine NOW!"

Dave Waldo

Yes, unfortunately the reservoir is dry. I have removed the offending item and will take it to a hydraulic hose shop tomorrow and see if he can fix it. I put plugs in the fittings left on the car but there was no fluid running out and that's about the lowest point in the system. I'll replace it and the reservoir (looks older than 40k) and see if the pump works.

You guys don't seem optimistic. :-)

Any particular hydraulic fluid ? Is there a site with recommended oils and fluids for the whole car ?

Any tips for bleeding the lines ?

Petza914

Uses the same fluid as the power steering, which is Pentosin CHF 11. That's supposed to be cross compatible with newer CHF 22, but some people have warned about that one being thicker and maybe not using it. Some of the chain auto parts stores and Napa may carry it.

Dave Waldo

I bought the CHF11 from Porsche, it's very thin. I had the line fixed by Pirtek, they cut the tube and braised on new fittings then a detachable flexible line. It works well, about 1/2 the price of a new line but it still has 2 flexible lines on it, the same age as the one that blew. Not confidence inspiring.

Thanks all, I have been lucky, it self bleed and the pump seems fine.

I filled the reservoir to maximum and left the end of line that fixes to the valve body behind the RHF wheel off but the fluid did not run, so I seated and tightened the line and started the engine. It almost emptied the reservoir within 5 or so seconds, I refilled it and the fluid cycled through bringing with it fine bubbles, not quite foam and the level dropped about another 1/2" over 10 minutes. I left it for a few hours then started it again the level had dropped about another 1/2" from it's last level so I left it overnight with no visible change and drove it today. It may have been my imagination but the 1st LH turns felt like it had a little extra roll but seemed good from there on. I live in a built up area so it was a fairly soft drive but enough to feel it working. After I returned there was very little, if any change to the fluid level. I'd say it's fixed :-)