Crystal Cranks

Hey Nelius, sorry I can't help with your ABS/PDAS problems as I have a C2 that uses a vacuum boost system not hydraulic. But if you are still getting problems with the "Christmas tree effect" I have two spare coils in my garage if you need to try them. I'm in Dublin.

porsche965

Hi Crystal Cranks,

Thanks very much for your offer i might just take you up on that if i have no luck with the ground strap etc. Can i get back to you on it after the weekend if thats okay, by then i should hopefully have the cause somewhat narrowed down. I'm in Kerry.

Regards,
Nelius
Ireland

SD

Looking for some help with my C4. Symptoms almost identical to this thread. Any news on how to fix?

I am suspiscious of the ignition switch but have yet to look/check.

Have replaced the DME relay, replaced the voltage regulator, checked that the MFA connections have fix, but no luck.

It seems that the battery is being switched on and off ...?

rarebear

related ? I have sometimes the ABS warning light on for a couple of minutes and then when driving it pops off... any advice is welcome
I am a Porsche driver for just 4 months and have always driven Alfa Romeos, so not much experience
with these Germans :-)

Henry964

I call myself a "veteran" of this dashboard lights problems, I changed coils and they got a lot better, I changed plug wires, distributor caps and rotors and they are almost gone...but not quite, when I drive for a long trip and pass over a small bump in the road ... and I have a passenger with me,they usually come back but not always.... go figure

drjsuh

Check out the tech areas section. There are several good write-ups on the pdas system and troubleshooting what the different combination of brake warning lights, etc. mean. I recently bought an older 964 C4 and my pdas and brake pressure warning lights stayed on longer than usual and got the warning beeps also one morning. I assumed that it was low brake/hydraulic fluid also, so I topped off (it was well within the range/level though already) and still had the same issue. After reading the tech area one of the posts mentioned a low battery level could cause this. Then I remembered that I had hooked up my iPOD to the stereo and left it in the glovebox assuming it wouldn't be much of a drain on the battery. Well, after I disconnected my iPOD, I haven't had the problem. So, it appears that it was simply the battery drain that caused the issue. Since it sounds like you just changed your battery, wouldn't be surprised if your issue is similar. Having owned several 911's, I know that our battery draw from just sitting in the garage is terrible for some reason (the porsches that I have owned are the only cars that I consistently have had battery issues and had to replace quite frequently). Hope this helps...

Bajaz

Check your coil and plug wires and replace your DME relay.
But most important, fully charge your battery!
Been there, and solved the problem by replacing my relay and always have a fully charged battery!
Good luck!

Petter :-)

medent

Edit

njansenv

I'd check the R34 relay first - I have a known good one in my C4 that you could use to test.

Possibly the connector at the abs/pdas computer - I had a similar problem, and ended up needing to replace both the ABS computer and front harness. Finally, it could be the ABS sensor.

It wouldn't hurt to clean out the accelerometers, but those won't cause the speedo to stop working like that.