PSM failure message at ignition

Good evening, I am having an issue with my 2007 Boxster . As soon as I turn the key in the ignition (even before the engine starts), I am having a "PSM failure" message. I can clear the error and the car drives fine, no problem. I have read the codes with my scanner and it's showing me a C153 "Communication steering wheel electronics control unit (drive)" under the PSM Control System. That same code C153 is showing up as well under the AWS Control System, AC Control System, and Gateway Control System. I assume it's a code that's related to some electrical gremlin? I have replaced the control unit, the battery , the brake switch, the clutch switch... no luck! I have checked the wiring on the ABS/PSM unit... no luck! I have read all PSM related threads and all of them seem to be talking about PSM failure while driving, not before the engine even starts... I found the schematics and I am now trying to locate the AY sensor and the wheel speed sensor... Any idea where I can find them, and what they look like? Thanks in advance for any help!

Does the dash warning go away as soon as you start the car? I cant tell for sure from your post if it remains, or is just there when you first turn the key?

The warning stays on all the time, as soon as I turn the key in until I stop the car. I'm able to delete it for a couple seconds when I am deleting the associated DTC, but it will come back immediately...

The wheel speed sensors are toothed wheels on each hub, with a magnetic proximity sensor that counts the teeth as they go past it to determine the rotational speed of the wheel. I'm not 100% sure, but I believe the Ay and yaw rate sensors are under the center console somewhere. Some people wire a switch to the yaw sensor to allow them to completely disable PSM for track use, so maybe search for a thread on that and someone will have some pictures. I don't mean to sound flippant, though, but if the code is referring an error in the steering wheel ECU communications, why not look there? ESC systems like PSM need the steering wheel angle signal (among other things) to infer what the driver is trying to do with the car in terms of its path, so if it's not getting a good signal, PSM can't function correctly. Some cars have the angle sensor in the steering column or steering wheel, and others on the input shaft of the steering gear; since this code refers to the steering wheel ECU, I'd assume that's where it is on our cars.

Thanks for the input. I did replace the steering wheel angle sensor as well, with no luck. Maybe I need to recalibrate it again? I'll give it a try... What strikes me is that I get the code in 4 different modules (Airbag, PSM, AC, Gateway), hence I am wondering if 1 (or more...) common component is failing when the car runs the diagnostic during the ignition process...

So I removed the panels inside the frunk, and I found a wire that is not connected... Am I missing a component, or this is just for an option that I don't have on the car? I read on another thread that the YAW sensor is located inside the PSM sensor housing, is it his box I need to open and check?

It's probably the wiring for an optional CD player. That was mounted in the compartment just to the right of that fuzzy wall you've taken out. I believe Porsche (very unlike them) prewired this from the factory since it was an option the dealer could install and make money on. If you read that here - let me know - I want to correct it. DO NOT OPEN THE BOX. No user serviceable parts inside. And no yaw sensor. I assume by "yaw sensor" you mean: Rotation-Rate Sensor For PSM Despite that image being a 986 rather than a 987, it's from the 987 factory manual, and I've touched that module just to see if it was there, and it is. Makes sense that's where it should be - it's roughly the center of rotation for the car. There is also an impact sensor for the airbag system in the car located in that general location - probably the same reasoning for that location. You can just touch it if you take the side panels off on the console (easy to do) but I doubt if you can replace it without actually removing the center console framework (which means removing everything in the console, radio, HVAC controls, multi-switch panel, dumb binny..) NOW - the other thing. I took a look. You haven't done an intro message in our new member forum. That's tradition around here if you want people to take you seriously and spend time looking into your problems. We have an entire forum dedicated to just that.. you can find it at: https://www.planet-9.com/forums/new_members/ - and we love pictures of your car. There are also several sticky postings in that forum that help you get the most out of Planet-9, and avoid stepping on toes and such. Worth at least scanning those. Wherever you read that it was located in the ABS/PSM module - stop reading. It's a bad source of information and will rot your brain.

So yes, I opened that ABS/PSM box, and there was nothing of interest (to me) in there... BTW, I did NOT read that on this forum, sorry for the confusion. I did find the rotation-rate sensor behind the front console, as you mentioned. I unplugged it and plugged it back in, no change. Except I now have a "faulty sensor" error message I used my scanner to look at the wheel speed sensors, they're all working properly... Could it be the "acceleration sensor" that's located in the trunk under the DME ? Is there maybe a way to just "uncode" the PSM option so the car doesn't diagnose it at ignition? Thanks for all the help!

I have changed the steering control ECU yet, no luck. Do I need to recode it? It's true I have used a used one, as there is NO stock for a new one... Just to make sure: We're talking about part #1 on the diagram, correct?

That certainly looks about like what I would expect a steering wheel ECU to look like, and I found that same image on a parts vendor's site with part #1 labeled as "electronic unit". Knowing how Porsche ECUs seem to need to be coded for the specific car that they're installed in, it wouldn't surprise me at all if it does need to be recoded.

Worth giving a try and recode it indeed... Do I need a PIWIS for that? Or a Durametric will be enough?

No idea there, sorry....

Thanks for the help!

Well, I installed a steering angle sensor today, tried to calibrate with my Foxwell NT 710 => "Calibration failed" and the PSM message is still on Will make an appt at a indy shop and have them investigate... Will keep you posted. Thanks!

When you tried the calibration with the NT710 - I've observed on most of the menus for electrical controllers on our cars - there is an option to replace the unit, first reading the car-specific info from the old one, and then program it to the new one. Did you do this? Might make a difference. If you're taking somewhere, I'd take the old and the new units along.

I know this is an old thread, but I was having a similar issue, and this thread helped me resolve it. In my case, I had the center console out and thought I had everything reconnected correctly. This thread pointed out the Yaw sensor, which I pulled out and replugged, and then I found out that the connector under the driver seat was loose (had that out also). Between pulling and putting back in those two plugs, my issue went away. Hopefully this can help someone else.