matthewjeans

Hi all,

I'm new to this forum but a long-term petrol-head and would be grateful for any thoughts on this.

I bought a 2006 Boxster S two months ago (75k miles) and it has been brilliant apart from an intermittent "PASM Failure" message which appears on the dash and the suspension goes into "teeth chattering" mode. Sometimes if I turn off the engine and restart it goes away but sometimes it comes straight back.

I have read every forum under the sun to find the answer and it is 100% nothing to do with the battery, turning the steering wheel etc etc.

It only happens when the car is hot, and normally when I have been in slow traffic or a traffic jam on a sunny day. It has never happened when the car is cold or even on fast local-road driving - always on the motorway at the end of a journey.

I would be grateful for any help/suggestions before taking it to an expensive dealer in London. I don't have any diagnostic kit.

Thanks in advance for any help.

Matt

Jason987.2

The most straightforward step one is to get a dealer or independent to read the codes...

My only other suggestion is to check the connectors on the 4 shock towers, make sure they're all properly seated. Also check the connector on the PASM control box (in the trunk)

matthewjeans

Thanks for your help Jason - that all makes sense and I'll check all of those connections. I'm just trying to avoid the time and $$$ of going to a dealer for now!

matthewjeans

Sorry Jason - where is the PASM control unit in the trunk (i.e. rear of the car)? - I read somewhere it is in the passenger footwell but this may have been for 997s. I can't find a photo of the location in a 987.


This location might explain why the problem only happens when hot as I have noticed the rear trunk gets hot (due to exhaust/engine proximity) when in traffic and maybe the PASM control unit overheats?


Thanks again for your help.

Jason987.2

Sorry for the late reply. I didn't get a notification that you had posted.
Were you able to find it? It's in the trunk, on the left side.

EDIT: It's in the passenger footwell in US cars:

Croc999

in my 987/2 the PASM controller is at the passenger foot well behing a thick carpet.

matthewjeans

Thanks for your replies. The PASM failure is now happening more often. Sometimes it is cured if I turn engine off and start again but mostly not. It never happens when car is cold- normally after an hour of driving minimum - I can't work out why this is the case - is the PASM control unit overheating??


Car is in for a diagnosis at an independent garage today and if they can't find out the problem I will take to Porsche Dealer.


The PASM unit is indeed in the passenger footwell up high behind some carpet - I suspect this will be my first piece of hardware to change if the diagnostic kit can't find a fault code.


I have checked the connections on the tops of all the dampers and they seem fine.


Any further thoughts very welcome!


Thanks again,


Matt

matthewjeans

Update - normal garage's diagnostic equipment couldn't access the fault code. Taking it to a Porsche specialist today - he says in 25 years he has never been unable to diagnose a fault on a Porsche - I'll update this thread tomorrow...

Jason987.2

My mistake about the location of the control unit.

If the fault is with the PASM control unit it may be because an internal solder joint has gone bad. In 2006 the electronics industry had moved from leaded to lead-free solder and there were some early issues with long-term reliability. The board in the controller is fairly simple and the solder joints can be re-flowed by someone who knows what they're doing. (I could do it for you in our lab - I work for a semiconductor company).

In any case you can buy a replacement unit from a dismantler. (I just did, as part of my PASM retrofit project into my 09).
It looks like as long as the hardware part number (98761810510) is the same (which is shared across a number of cars), it can be reprogrammed by PIWIS to the particular car.

May I ask a favor? Could you
a) save the PASM box if you indeed replace it; I'll pay you to ship it to me.
b) go to my thread and answer what you can?:
https://rennlist.com/forums/987-981-...with-pasm.html

Cheers

matthewjeans

Thanks Jason - will definitely send you the PASM box if I get a new one.


UPDATE - The Porsche specialist just called - the codes say it is either the rear body acceleration sensor or the PASM Control Unit itself. They say that they strongly believe it will be the sensor rather than the control unit - has anyone heard of this before?


The sensor is currently out of stock in the UK and Germany so I am planning to buy a 2nd hand one online and get the garage to fit it - 2 hours labour apparently - does this seem fair?


Maybe I should just replace the sensor AND control unit at the same time to be sure?




Thanks again for any thoughts!


Matt

Jason987.2

The acceleration sensor is dirt cheap used. Replace that first.
Here's one in the UK:

http://www.ebay.co.uk/itm/Porsche-91...-/121961532587

There are 2 part numbers that will work on your 06 (and my 09) according to the Atlanta Porsche parts database:
99760611100
99760611101

http://www.porscheatlantaperimeterpa...760611101.html

Replacing it takes 15 minutes with a pint in one hand. It sits under the DME (main computer) in the left area of the trunk. Just lift the carpet hold-down thingies with the tines of a fork, unclip the small connector, and remove 2 10 mm bolts.

matthewjeans

Jason - thanks, that's very helpful - I think I'll call the garage who's quoting 2 hours and ask them to reduce this or I'll do it myself.


Before I do this, is there no coding etc that needs to be done? Can I simply remove the old sensor, swap the new sensor in, turn the ignition on and all will be ok - it doesn't;t need to be coded or anything?


Thanks again - very much appreciated.


Matt

Jason997.1

Correct. No coding. The sensor is analog. I strongly suggest you diy. It's way too easy. Way easier than an oil change. You can go look at it now.

matthewjeans

Final Update - I had the rear acceleration sensor (bought 2nd hand on eBay for £30) replaced by Charles Ivey Porsche in Fulham, London - who were excellent from start to finish.


Whole job including diagnosis, fault-code reset etc. and oil top-up, was £200 and it has cured this issue. I guess the rear sensor somehow became sensitive to heat - i.e.. this is why it never failed early on in a journey.


I can't find anyone else who has had this same issue so I hope this may help others.


Car now going like a dream with the amazing ride that PASM provides...


Thanks for your help Jason.

SevenSpeed

I have a 2006 Boxster that just gave the failed PASM message once when it was hot. So, I got to where I can see the DME in the trunk (pic 2), but I don't see the acceleration sensor anywhere. Is it hidden behind the DME? Maybe pic 2 above is of a different model year (??) Any help finding the rear acceleration sensor in a 2006 Boxster would be appreciated.