ABS and PCM failure

[AndrewEllinas]

This is my first post in 2012, so Happy New Year to you all.

I hadn't used my 2004 TT for about 5 days till yesterday. After I had driven for about 10 minutes two warning lights came on for ABS and PCM failure. As I was on the motorway, I had no alternative but to continue to drive for another 10 minutes and luckily pulled into a service station.

I switched the car off and then back on - and the warning lights remained off. They are still off.

So, any ideas what might have happened and does it need to be investigated now or do I assume it was just 'one of those things' that happen with Porsches and keep my fingers crossed that it doesn't happen again?

 

[Richard_Hamilton]

The three common causes are:

MAF Sensor (usually throws the ABS & PSM lights when giving it the beans)
Brake Light Switch
An ABS sensor

A diagnostic check would show up what caused it.

 

[AndrewEllinas]

Thank you Richard.

It's due into Hatfield OPC for an MoT in a couple of weeks so, as long as they don't come back on, I'll leave it till then and ask them to investigate.

 

[AndrewEllinas]

I took the TT into my OPC for the MoT and because it started to misfire and they found:

'cyl 3 spark plug wet, replaced however still misfired. Replaced coil pack and again still misfired. Checked multiplug on DME unit, all okay. Feed to coil pack voltage 0.3 should be 12v. Drop rear engine to gain access to coil pack loom."

Parts used were: spark plugs, metal sealing R, cable ties, O-ring, A/C O-ring and pentosin.

The loom was not replaced.

That was at the end of January and cost me £2.5K.

I've used the car very little since then. Yesterday the ABS and PCM failure lights came on again.

I've called the OPC today and am waiting for a reply.

Any ideas as to what the problem can be?

 

[AndrewEllinas]

From: http://www.planet-9.com/cayman-boxster-problems-complaints/43055-psm-failure-abs-failure-both-lit-up-today.html

Re: PSM failure, ABS failure both lit up today
This happened to me about 2 weeks after getting my used 2008 CS. My independent diagnosed it as a brake pedal switch that was starting to fail. Same issues with abs and psm going off and clearing with a restart.
I got the brake pedal switch and after changing it I have not seen the warnings again.
Might not be the same issue but that is what mine was doing and what fixed it.
The brake pedal switch was under $20 fwiw

And: http://forums.pelicanparts.com/porsche-996-997-forum/366950-abs-psm-problem-cured.html

 

[AndrewEllinas]

I took the TT to JZM in Kings Langley.

They diagnosed it as a faulty brake switch which was replaced with a total cost of £58. The smallest bill I've ever had from a Porsche garage.

That's a relief!