PIWIS Solved 958 Cayenne Exterior Lighting Issue

Car model: Porsche 958 Cayenne

Issue:

Standing outside vehicle with car off I press lock on the fob and everything happens as I expect: lights flash and turn off… Chirp chirp… Car locks… AntiTheft light starts blinking…
Same results when locking manually.

But exactly 20 seconds later something unexpected occurs. Exterior lights start coming on!

Then 10 seconds later more lights come on!

And all these lights stay on until the battery dies.
The battery was completely dead upon purchase and they swapped it out before I left the lot.

Issue reproduces for various positions of light selector switch.

If I walk away from the car with the car unlocked then eventually (couple of minutes?) the front lights come on but I think not the rear lights.
​​​​​​

Solution:

I went ahead and ordered a pre-owned ballast for $26 hoping that might be it. Just ordered a Porsche PIWIS tester as well.
Good call on a thorough visual inspection I’ll do that.

Let’s hone in on what stood out most from PIWIS diagnostics:
1. The roof console is a sub-section of the rear electronics module, but the roof console part number could not be read.
Possibilities I thought of: Wires are missing/incorrect; One or more wires are grounded; Rear BCM was replaced but as wrong revision or was coded incorrectly; Rear BCM was replaced but must be mated to the car via dealer online coding; Roof console is sort-of seen but needs to be taught
Evaluation: Unlikely that rear BCM would fail or be removed-even by a savvy thief-therefore unlikely that the BCM was replaced. Some features of rear BCM I could control via PIWIS so it is probably coded correctly. I verified all wires exist except that alarm horn wire but no evidence in harness of it being cut. Let’s focus on the idea that roof console cannot communicate and see what wires it shares with BCM.

2. Rear-end electronics board has one error: Communication with LIN bus.
Possibilities I thought of: Wire is missing; wire is damaged; wire is grounded; Board is bad; Board is coded incorrectly
Possibilities suggested by PIWIS Fault Finding: “Short circuit to B+/ground or open circuit in the line.” , “”Cancellation of communication due to bit error.”
Evaluation: I opened up the module and visually inspected the board for burn marks or melted components. I visually inspected the wires as well after popping the trays of wires out of the connectors. They have little tiny numbers printed on the connectors, the trays, and the sockets that need to be lined up.
I only have a couple hours a day where it was possible to work on car so I went ahead and ordered a replacement roof console for $70. I can always resell it if I don’t need it. It included the connectors chopped from the harness and those connectors came up clutch later.

The console arrived yesterday so I connected to PIWIS and got the same errors. I was unable to teach this roof console as well. This result further points to the wiring being the issue.

The wiring diagrams for PIWIS have an added advantage over those in the workshop manual in that you can click one terminal end and it will zip you over to the other end. I read all wires for the rear electronics module for relevance:

Terminal 33 on connector A is titled “LIN 1”, which PIWIS told us cannot communicate. Scrolling down, I see that black/yellow wire has a few things spliced together.

We can see that the splices on that LIN1 wire from rear BCM are:
-Pin 5 on the panoramic roof connector (visible in roof console cavity)
-Pin 1 on connector A of the Sliding Roof (no idea where this is)
-Pin 12 of connector A of the Roof console
-Pin 2 of connector A for the interior mirror (rear view mirror).

I set my multimeter to resistance to “tone out” the wires I know the location of and see if they are connected. I used a wire insulation piercing probe on LIN1 at the BCM connector black/yellow wire (if you don’t have one you should get one). Sure enough they are all connected, ringing and registering ~1 Ohm. I see what the resistance to ground is (expected to be infinite, aka open circuit) but the meter rings and says 60 Ohms! Might be onto something here! I see in wiring diagram that BCM has a LIN 2… I try to tone that with ground and get infinite resistance.

Next I wanted to re-run the wires directly. I didn’t want to cut any factory wires if I didn’t have to because there isn’t a whole lot of slack and I don’t have many of my proper tools on the road with me. I just had a $5 harbor freight cheap-o crimper set,
Three of the four wires I want to replace are the same type of pin; coincidentally and conveniently I have many spare of these already crimped to 4 inch strands of wire thanks to the connectors from used ebay item. I slide out the factory pins in question and run my own wires. The small pins could be removed fairly easily with a small flathead or pick tool.

For the bigger wire with bigger pin in the panoramic roof connector I used my VW pin removal tool that I bought for changing the fuel flange plug on the 955 CTT.

That way I could have connector connected but not that wire with the mystery ground on it. On the other side of connector I just shoved a spliced end of my ghetto wiring harness lol.

I double checked my work… popped in the key… and the dome light sprang to life! Great sign! I connected PIWIS and could read the roof console part number.

I had new errors but probably because I couldn’t find the 5th wire in the splice so sunroof still not working yet. Time to plan the route of my new wiring harness (obviously I’ll make it much prettier, safer, protected, and well-labeled.

Thanks again to those following along and contributing ideas.
The experience makes me want to find a few dirt cheap Porsche or VW wiring harnesses that have crimp pins of various sizes to aid in any future electrical troubleshooting adventures.

Credits to @ Jonathan H

Good source of PIWIS:

Piwis 3 V38.900.000 PT3G with SSD 128G with Panasonic CF-MX3 Laptop

https://www.obdii365.com/wholesale/porsche-tester-iii-diagnostic-tool-with-panasonic-cfax3-laptop.html

or VXDIAG Piwis 3 V38.900.000 with SSD 240G & Lenovo T440P Laptop

https://www.obdii365.com/wholesale/vxdiag-vcx-doip-porsche-piwis-iii.html

https://www.obdii365.com/service/porsche-piwis-fixed-cayenne-exterior-lighting-issue.html

PIWIS II or PIWIS III? Why a mechanic needs one?

Part 1: Why you or your mechanic has to have a PIWIS

A PIWIS is the factory developed diagnostic and repair tool. It stands for Porsche Integrated Workshop Information System. Porsche dealer technicians use this tool to perform a multitude of diagnostic and repair functions on your car. There are 3 generations of testers, the original which I believe can handle cars up to the 2014 model year, the PIWIS II which handles cars up to and including the 2017 model year and the current PIWIS III which handles all cars including the 2020 model year. Naturally if your car is under warranty, then you don’t need this tool. Let the dealer handle any issues that come up. However, if you have a Porsche which is off warranty, watch out, your dealer charges crazy high hourly rates, mine is currently at $269 an hour, and also charges you parts at full retail. Go to a dealer for a brake job, and he will quote you $4000. You can do it yourself for $600, $900 with factory parts. Need an O2 sensor changed? There are 4 on a Porsche and the dealer will quote you $1200 for one, and then will recommend that they be changed in pairs so now you are looking at $2,400. A quick lookup on Rockauto.com shows you can buy a Bosch OEM O2 sensor for $60. Luckily, the 02 sensor change does not require a PIWIS but the rear rotors do as many have discovered here after doing their brakes. As many of you have noted, you can only lease a PIWIS from Porsche if you are a member of their PPN. Porsche Partner Network. Your local shop can apply to become a member and then pay $18,000 for his tester for the first year and $12,000 a year after that. Very few shops will pay that to repair only one model of car. Luckily our friends in China have cloned the PIWIS. It’s a little buggy and wont update since you aren’t connected to the PPN but the Chinese have disabled the function which tells the interface tool to check with the factory to see if it is legit. What is it, it’s basically a pc with some added software and a special interface between the car and the PC The PIWIS II is a Vista based ( yikes) windows pc The Chinese have improved on it, adding an SSD and some have updated the OS to Windows 7 but I don’t recommend that version. The PIWIS III I haven’t seen yet so I don’t know if it is still a windows pc. Both version have a multimeter function built in but the Chinese version of the PIWIS II doesn’t ship with those cables. The PIWIS III has a built in multimeter and oscilloscope and the cables are included. You see the interface online for the PIWIS II for $369 but that doesn’t include the necessary software. Buy the entire device for $769 which includes a pc, software, interface and car connect cables. A PIWIS III sells for $1999 down from $6500 last year. Look at this web site as an example of how sophisticated the clone market is. You can’t tell the difference between a factory tool and a clone. Now why do you or your mechanic need one? Well here’s what you can do without one

Change spark plugs and ignition coils. (The engine module is self calibrating and will learn new parts automatically)
Change front rotors and pads
Change switches,
Change washers, wipers window motors, door locks
Change most engine sensors
Change your own oil (but you won’t be able to reset the service interval)
Change differential oil
Change battery (But you won’t be able to tell the car you changed it)
Change bulbs

Here are some basic things that you can do that require a PIWIS
Change the rear rotors
Change any suspension parts
Change seat motors
Change any control modules (There are 27 of them) All need to be coded with the VIN of the car
Change the battery and record the change with the gateway module
Reset the service interval

Change the PDK oil (you can actually do the PDK fluid change without the PIWIIS , well a simple fluid change, you might need it if you replace the PDK filter. the reason you might want a PIWIS for the fluid change is to monitor oil temperature. The V8 needs the oil to be a certain temperature for all the oil in the cooler to drain. The v6 wants a certain temperature to be hit behold you check the level in the top up procedure. In both cases you could likely run the car for ten miles to achieve the temperature).

Change headlight components that aren’t bulbs
Change clock spring ( will require codes which only the dealer can get but you can buy from the Chinese

Most importantly, as many of you have discovered, it is nearly impossible to diagnose repair issues without one. The Durametric device just doesn’t come close to providing the information you need and many of the error code labels it provides are simply wrong and will lead you changing parts that don’t need changing. At $769 which is less than 3 hours labor, you can see everything a dealer can see about your car. I have a 2 and I’m going to a 3. If anyone is interested, I can try to post a video of the PIWIS II. It has a simulation mode for training purposes which is helpful. There are 4 programs in the PIWIS, the diagnostic, which is the main program for service, a wiring diagram program, a fault finding program which I haven’t found to be useful running offline and the multimeter function.
If you can share one with a buddy or some Porsche meetup groups that would be ideal. My recommendation, don’t let anyone do repairs on your car that doesn’t have one.
Here are some basic pictures

This is a Porsche PIWIS II which was originally on a Panasonic toughbook shown here

The menu options

This is the unit going into the diagnostic program and it shows a picture of the interface.

Parking brake module extended Identifications. This is where you can change the VIN on a used part or add it for a new part

Part 2: Why you need one piwis III instead of piwis II?

For the newest Porsche model after 2017 year (i.e 2018 Macan), requires piwis tester 3;

For the older Porsche model (i.e a 99 Boxster), don’t need the newest version, then piwis 2 is okay.

Question: As I’m researching this myself, given that you don’t have a model year that requires it, what is driving you to upgrade from piwis II, to piwis III? Is it just this: “The PIWIS III testerhas a built in multimeter and oscilloscope and the cables are included.”, or other factors that you can note here, for reference?

Reply:

I also have a 2018 Macan that requires the piwis3. I hope to help people in my community and I also plan to rebuild another. I’m excited my PIWIS III arrives tomorrow. I will review after I test it out. I have PSM module arriving Saturday that will need the module replacement procedure.

An interesting thing happened to me the other day. I had just received my PIWIS III and was going to use it to change out the PSM module and before I did I had it run a full diagnostic. At the time I didn’t realize that the unit was in development mode. My PIWIS 2 would only show one code, a faulty recirculation servomotor which I have struggled to physically change due to its location. When the diagnostic was complete two things happened; one I realized it was in development mode since all the responses were in German (in development mode the menus can be changed to English but the responses from the modules appear in German) And two there were more error codes. After having Google translate the German responses I discover that the b piller servomotors were mechanically jammed. It also found a fault in the brake light switch which was working properly. I switched the unit to after sales mode( the dealer mode) and those codes weren’t there Then I used the unit to monitor the servomotors in question. What I discovered was that they were indeed not moving from 0 to 100. After finally figuring out where they were located (under the front seats) I pulled one out and took it apart and the motor shaft was seized. Un seizing it didn’t do enough to fix it so I ordered 3(one for the recirc). Anyways the point is that developers mode not only tested the motors it tried to run them from stop to stop which normal mode does not. The brake light switch after checking the voltage while pressing on the switch was showing only 7 volts so it was partially shorted something else missed by the regular mode. If you have mysterious issues with no codes and have access to Porsche tester, try running it in development or engineering mode as it is sometimes called, and see if it reveals any new codes.

Question:

Do you know if it is possible to activate the rear DRL and the LED Matrix headlamps with the PIWIS III?

Answer:

activation codes are not included with the tester. You can add them if you have them but this is an online programming function and the dealer must pay Porsche for the options that he installed. When he sends a work order to Porsche he receives the activation codes then enters them into the PIWIS. Now there are some Russians who have hacked porches codes and will sell you an activation code for new options. I haven’t tried them but I did pay $125 for my original activation codes so I code reprogram a pcm and a new clock spring.

Question: PIWIS III clone or original, which one should i buy?

Answer:

I recall now that I encountered a Chinese PIWIS at a local “indy” shop. I had my Turbo in there in Sep. of 2019 to get new O2 sensors installed and the tech — recently from the local Porsche dealer I use — was there and after the sensors were replaced he grabbed what looked like a PIWIS but when I expressed surprise that an indy shop would own one he told me it wasn’t the real thing but a Chinese clone. He said it worked pretty good.

Question:

PIWIS Chinese knock-off is way too expensive for me and offers no online updates. Is it true?

Answer: No. It depends on where you buy one Piwis 3, this one comes with U disk update tool and allows user to update online:

http://www.obdii365.com/wholesale/porsche-tester-iii-diagnostic-tool-with-panasonic-cfax3-laptop.html

Enjoy!

http://blog.obdii365.com/2020/04/27/porsche-piwis-ii-or-piwis-iii-which-to-buy/

How to Check Porsche Engine Oil Level by PIWIS Tester?

Checking the Porsche engine oil level makes more accurate than the normal procedure with the instrument cluster screen and on top of that, it tells you how much oil you have to top to be at max level. This will be used every time we change our oil.

Here is the procedure:
WM 170101 CHECKING ENGINE-OIL LEVEL USING THE PIWIS TESTER (CAYENNE, CAYENNE GTS, CAYENNE S HYBRID, CAYENNE S E, CAYENNE TURBO, CAYENNE
(3.0)) > CHECKING ENGINE-OIL LEVEL

Information
The PIWIS Tester II instructions take precedence and in the event of a discrepancy these are the instructions that must be followed. Deviations may occur with later software versions.

1. PIWIS Tester II must be connected and ignition switched on.
2. Start the diagnostic program and select the required vehicle.
3. Select the DME control unit in the control unit overview. Press [F12] to continue.
4. Select the Maintenance/repairs menu. Press [F12] to continue.
5. Select the Oil filling function. Press [F12] to continue.
6. Start the engine and let it run until an engine oil temperature of 90° C is reached.Rev the engine if necessary to heat the engine oil to the specified temperature.
7.The oil level measurement process starts automatically as soon as the engine oil temperature
of 90° C is reached.
8. Switch off engine.
9. Add the quantity of oil displayed on the PIWIS Tester 2.
10. Disconnect the PIWIS Tester.

With the Launch X431 V it is located in the “Oil filling” special function menu of the DME and here is how it works:

Test on going:

Result (0.9 liter to add):

www.obdii365.com

http://blog.obdii365.com/2020/02/28/check-porsche-engine-oil-level-by-piwis-or-launch-x431/