ProgRockJunkie

It took some time to get to this. The shop that did the work was unclear as to why we would need a charger connected, but did so. We noted the code and then proceeded with the calibration. On entry of the first height measurement, the process aborted every time. We tried it with both old and new PIWIS, and with and without the charger connected. The tire pressures were within normal range, TPMS active with no complaints. I considered playing with the tire pressures, but didn't want to waste the shop's time. Is there anything else to try before I replace the ride control module?

Thanks...

J'sWorld

Looks like you have a FSM. It pretty much says you will get a red triangle if the CU is faulty. You need a charger connected because the Cayenne is very power hungry and you dont want to corrupt any data being transferred due to low voltage. Also the PIWIS can be powered through the obd port or by an internal battery/charger. Pretty much anything that has to do with coding/programming/etc. needs to have a charger connected. This is stated over and over in the FSM to the point of redundancy. I thought the shop you were using had an AUTEL? Why did they not try one of the PIWIS the first time if that is the case. When you say PIWIS, you mean one and two? IF its a genuine PIWIS they probably have it on lease and there would be no need to keep both the 1 and 2 version as 2 supercedes. When you don't have valid fault codes to deal with things get dicey and that's really hard to diagnose over the computer. The PIWIS has guided fault finding and this would help in your case. Not to be rude but if the shop was unclear why you need to have a charger connected maybe they don't have any buisness working on your ride?
With the PIWIS you can look @ actual values of every component in that subsystem and see what the CU is seeing. You can also perform activations of every component. Some people say "Oh you dont need a PIWIS to work on these cars". "Oh no, the I-CAR scan wont hold your hand like the PIWIS does". Well the fact is there are over 40 control units in the Cayenne. Porsche has taken great time and effort to protect their intellectual property to ensure that the aftermarket cannot steal their buisness. Even then there is so much that is not published. for example many of the sensor values are not published. You could test them but how to know where you are @? Porsche does not want certain things diagnosed, they want it replaced. It comes back to generating revenue. If you take the capability away from the tech, the tech only has what Porsche instructs and one work flow to follow. If it were me in this situation, I would start @ one end of the system and go thru all of it. Diagnostics is process of elimination. You need technical reference material and the right equipment in this case. Even then with the best tech, its going to take time and that can get very expensive.

ProgRockJunkie

I've worked with more than one porsche shop in the area. The one I took it to this time had the old PIWIS and the new one. The other shop did not have a PIWIS.

You said it looks like I have an FSM? All I'm guessing is faulty service module. I don't mind at all doing my homework and working the problem, but I'm a novice at this stuff.

So for a layman, what would you suggest as the next step? The PIWIS would cancel the calibration at entry of the first height measurement every time. We did have the charger connected for a few attempts. Suspension was set to normal height. Doors shut if that matters. TPMS active and not complaining if that matters. I'll buy the ride control module if that will get us past this, but is this what you recommend as a next step?

Thanks much for all your help.

J'sWorld

Maybe the Can Bus is timing out? Really hard to say based on what we have here. Are you erasing fault codes prior to and after? I've sent you a pm with a link and that should help.

ProgRockJunkie

Thanks for everything in email. Appreciate it. Will update the thread as I go.

Off the wall question here, what's the group think on eliminating the air suspension altogether and what's the best solution, Arnott perhaps? I have an email out to they and one other conversion supplier asking what ride height they'd leave me with and what happens with the idiot light on the dash. Just curious. I could see this system becoming a real drain over time. Already rebuilt the compressor, had the actuator/sensor issue, now this.

ProgRockJunkie

Quick update, about to start working on this again. I was stuck not wanting to pay the "discounted" price for porsche part 955-618-301-42, had been watching ebay for a while for a used one. I'd called Porsche and VW parts departments but couldn't get any help cross referencing the appropriate corresponding Toureg part. Finally realized that the one new Porsche example listed on ebay included verbose pictures which included the corresponding VW part number More precisely, it's a VW part that Porsche notes their corresponding part number on by hand on a comment line So in case anyone else ever needs this, Porsche Suspension Control Module part number 955-618-301-42, which superseded 41 and 40, would seem to be VW part number 7L0907553F. Picking one up and will test my assertion. I have proof positive pictures from one on Ebay, but I won't close the book on that until it's installed in my Cayenne and hopefully calibrated.

ProgRockJunkie

Final update. I waited until I had a laundry list of other service items, brake booster replacement, oil and filter, headlight bulb, changed the diff oil, replaced the diverter valves...and watched ebay for the least dubious replacement suspension control module. The one I eventually bought was the VW part number of course, and had recently come out of, get this, a Cayenne Turbo. So either it came with the VW part number installed at the factory, or someone else replaced with the VW part. In any event, it looked to be like new, mint, for $100. The Cayenne part number lists for $1100, absolutely outrageous, and if you're lucky you can find it on sale for $700, and it's the same thing. Again, the 955 Cayenne suspension control module maps to VW part number 7L0907553F. We swapped it out and it calibrated perfectly, didn't even need the PIWIS as recommended above though had one available if needed. That stupid idiot light started blinking at me two years ago and has been solid on for more than a year. The initial cause was corrected, but the module was fried and wouldn't recalibrate. Replaced with VW # 7L0907553F and it's fine.

Thanks to all who gave input.

I'll write a better review later, but many thanks to Zoli of Euroboost in Sterling, VA. Find him on Facebook. Ace mechanic and charges about 20% less than the more established shops. Young guy that really, really knows his stuff. He's taking care of all our cars now, 2001 911, 2006 Cayenne TTS and 2012 MB GL450.

J'sWorld

$100.....

That's whats up! Congrats!

ProgRockJunkie

Can be had for $80, but at that price point it was worth looking at both condition and the vehicle it came from, supposedly anyway.

​​​Thanks for your help in all of this. I appreciate it.

cordsig79

That is exactly what happened with my CU. Bought a salvage on ebay for 100 bucks, plug and play. Then we tweaked it to factory settings.

ProgRockJunkie

NOW you tell me...

J'sWorld

I told you early in the thread brother...... I also referred you to Cord's thread. But the the good news is that you ended up getting it fixed for great price and your able to enjoy your Cayenne again.

ProgRockJunkie

Well hell. Maybe I read it all back then, or maybe I glossed over and didn't pay attention well. I do tend to like to learn lessons the hard way. Thanks for trying to get through my rather thick skull. But yes, good news is I worked through it, convinced myself what part mapped to what and got it done.

hahnmgh63

Congratulations, always good to solve a annoying mystery. Wish I had followed this saga earlier. I will say that the Porsche E-81 TSB (the one that shows the dealers the parts and tools to convert a Turbo to the E81 Powerkit not ordered that way from the factory) only shows the Level Control Unit changed, none of the sensors. The specs say the new LCU goes to a little lower setting than the stock Turbo unit. Of course there are all of the other E-81/Turbo S parts that go with the kit. The E-81 Power kit was a retail of $19,995.00

jeff spahn

I tried soldering a cracked post on my CU as well. Didn't solve the problem. It appears that the rear shocks are not going up and down properly and this is throwing the fault. I ordered a module off ebay. for the $100 its a cost effective attempt to solve before I go to the dealer.