Computamedic

Many of you will probably remember the continuing problems I have had with my C4 and the annoyingly consistent occurrence of the PDAS/ABS alarm when driven any distance. Over the summer the problem seemed to get worse (i.e. you could driver shorter and shorter distances before the dreaded alarm struck. I discovered that the problem was definitely temperature-related but that didn’t help diagnose it.

In desperation I recently booked the car in to JZ Machtech to let Steve have a go at it. Interestingly, Steve insisted on looking at the ignition system before attempting to look for more complicated issues – he said that many cars had displayed similar problems that were caused through HT tracking. Low and behold, he discovered that both the coils were showing very bad tracking damage, as were both the distributor caps and rotors. I’ll post some pictures of the old parts on my web site later in the week if anyone is interested.

Having replaced both coils, distributor caps and rotors as well as a couple of “less than perfect” cable ends (sum total almost £400) is seems like the car is behaving at long last. I managed the drive home from JZM without once seeing the age old problem!!! I’d still like to get a few more trips under the belt before getting too enthusiastic – but it’s looking good.

Regards


Dave

Computamedic

If anyone is interested I have put some pictures on my web site of the offending articles causing my PDAS/ABS problems. You can follow the link to http://www.computamedic.co.uk/Porsche/PDASABS.htm. If you click on the lower image it will give you a higher resolution picture and you can clearly see the tracking on the distributor cap and rotor. The inside of the cable plug looks like a piece of 3 month old cheese!!!

Regards


Dave

garrett376

It's amazing how many problems bad electrical parts can cause on these cars! Thanks for the update!

clashmin

has this fixed the problem? I have a 90 c4 and the awd (red) light comes on with the buzzer etc at about 9 miles. If I shut off the car and restart, the red awd light will come on after another 9 miles or so (7 to 10 miles). The motor is recently rebuilt (it had this problem before the rebuild) by GT Performace in Maryland and is being broken in.

Computamedic

It's interesting that you ONLY get the AWD (PDAS) light with the buzzer. Are you sure your ABS bulb is working?? I assume you also get the (!) main warning light too?? There are very few conditions which will give the PDAS light ONLY. The main one is a drop in pressure in the hydraulic system. This can be caused by a failing pressure pump or a faulty pressure switch.

It would be useful to confirm that your ABS light illuminates when you turn on the ignition just to prove the bulb is OK. Only if BOTH PDAS and ABS come on is it likely to be a similar problem to mine.

Regards


Dave

clashmin

i checked and the anti-lock light (ABS) is working fine. Scenario (everytime): I drive between 6 and 9 miles and the red AWD light, ! and horn come on. It does not matter if the car is hot or cold. If the red AWD light, ! and horn come on, i pull over to the side of the road, turn the car off and back on- and the same thing will happen after 6 to 9 miles. One note- my front tires are severly worn and the back tires are fine- there could be a rolling diameter diffence.
thanks,
Dave