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PSM ABS warning and Tiptronic problems

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996 (2002) C4 Cab Tiptronic

Hello, I would appreciate some comments to enable me to have a more informed conversation with OPC.

Having driven with some vigour and heavy braking I got a PSM and ABS warning warning on the dash.

I left the car on the drive for 20 minutes before re-starting, at this time the warnings had cleared. I drove around for 5 minutes testing the brakes - no further warning messages appeared.

The next morning the battery was entirely drained.

After having the battery replaced I now have a new additional problem - Tipronic in "Safe Mode".

Having looked through the previous owners paperwork I notice that the battery was replaced just 6 month ago (I have only had the car for 3 months).

This leads me to believe there may be a deeper issue yet to be found/addressed.

So my questions are:

1) PSM ABS warnings seem common - don't worry if they clear down?

2) Is there something relating to the PSM or ABS that could be draining the battery when the car is off - I'm wondering if there is something failing to power down fully??

3) Is my Tiptronic in "Safe Mode" the result of the battery being replaced and can I clear the warning? - or is it likely to be another unrelated problem?

Thanks in advance for taking the time to respond..

Edited by griffige
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1. If you were on wet roads driving vigorously then some wheel slip is expected. PSM and ABS lights can be caused by a bad brake light switch or bad MAF. But when one of those happens they usually stay on.

2. Probably not. It would be best to have the battery tested for both load and specific gravity of each cell. Batteries sometimes do go bad. Best check for some other current draw on the battery when the ignition is off. Normally it should be in the 40-60 ma range with the car off.

3. Not usually - but you will need a PST2 or PIWIS to reset the Tiptronic - so they should dod a full car scan while they are doing that.

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It could also be your alternator going bad, cutting off intermittently, since the battery was only 6mths old. Then with the new battery in, it was still not being charged, if the alternator is bad.

I say this coz' the last time my alternator went bad, I had similar warnings of the PSM, and Tiptronic went into safe mode (4th gear). Then followed later by "Christmas lights"! You'd be surprised how much electronics are dependent on full constant power on our cars, they can't run on battery alone for too long, probably not more than 15mins.

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Car went to OPC yesterday - they have confirmed a faulty/broken alternator.


Car back now - all fine... interestingly the Tipronic seems far more responsive now.

I wonder if the lower power levels it was running on affected the perfomance of the algorythm it uses when determining driving style etc..

Thanks again!

Edited by griffige
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