pat056

I haven't cleaned the connectors yet. I'll try that next.
I'm not sure I would have to reset the fault since once I turn the car off and back on, the light is out and stays out until I move foward. Doesn't this rule out having to reset the fault?
BTW, the ABS isn't working, so it's not just a light thing.

dfinnegan

Another possibility, though remote, is that the central informer connections are causing the fault.

I had a master alarm (!) light that would occasionally come on alone. I diagnosed it by wiggling the connector harness to the central informer and could get the light to come on and off.

After disconnecting the connector, cleaning it up and reconnecting I've not had the problem.

The central informer is up under the dash on the left hand side.

pat056

Hmmm...
I had a new fuel cell installed a few months back. The installer wired the low fuel light on the fuel cell to the low fuel light already on the dash. The car has only been driven a few times since then. Maybe the problem's under the dash.

Richard Curtis

Not to hijack this thread, but I have a similar problem that occurs only occasionally and only when driving on very bumpy roads. My ABS light and the (!) light will flash on and then go off immediately. It seems always to be associated with hitting a bump in the road. I assume this is because of a wiring fault somewhere. I'll try cleaning the connectors as noted earlier in this thread, and checking the brown ground wires for any breaks. Any other thoughts?

pat056

Richard
Let us me know what you find? I had that problem. That's why I had the reset switch installed. If I hit a bump and the ABS goes out, I just reset it. Has worked great...up to now

Gregg-K

Any update from anyone on a solution (or at least progress) with this issue ?

Thanks,
.. Gregg

Richard Curtis

I did remove the connectors and sprayed with electrical contact cleaner; reinstalled. Light has flashed on twice since. I talked to a independent Porsche mechanic and he looked a bit perplexed; said it would require some trouble-shooting. I'll be driving the car on a 800-mile roundtrip this coming weekend so maybe I'll learn something from that, since I normally don't drive the car very much (<1,500 miles in past year).

IrocMan

+1 on the 'clean sensors and connectors' including the large AMP connector on the ABS ECU.
I had the problem and couldn't find the culprit. After cleaning all, never happened again.

IrocMan

Richard,
Did you include the ECU connector ? Did you also check the charge tension the alternator generates? Seems like some folks had to rebuild the alternator (at least change he charcoals) to get rid of that light.

Good luck and please let us know. Experience is a good value.

Richard Curtis

I only cleaned the connectors. Where are sensors located and what do they look like? And what is the "large AMP connector on the ABS ECU" and where is it located?

IrocMan

The ABS unit is located at the front of the car under the carpeting. There's a connector on the electric valves also (on the right of the car). Also the pressure valve and sensor are on the booster pump (the motor that looks a bit like a golden engine starter on the very front of the car behind a plastic cover, in front of the battery. But this sensor failing (or connector being oxidized) leads to an overpressure and when you put contact ON and you can hear it having difficulties compressing fluid (the motor is powerful enough to boost up to 65 bars, sensor cuts at 55 bar if I remember well) so this is easy to diagnose.
The connector on the valves, on the right, is a more common issue, there's often some very minor fluid leaks that help this connector oxidize. The ABS unit is just under if I remember, check this connector also (that's the large AMP connector). Used some electronics/connector spray for that purpose.

Richard Curtis

If ever a photo was necessary to understand what's what. Anyway you could shoot a photo, label it, and post it? It would be greatly appreciated.

IrocMan

None of the components are at the original place in my car unfortunately... this is why I state "if I remember well"

Let me check on the web, I'm pretty sure I can find a pic and add labels on it for you.

IrocMan

I realize you have a C2, which makes it mush simpler
I don't believe you have the ABS valves on the right. However you must have a central unit like this one :
http://farm3.static.flickr.com/2143/...e751e1.jpg?v=0

And as you can see on the picture the pins are oxidized and needs to be cleaned.

This picture now:
http://www.porsche964.co.uk/technica...R1_12_0001.jpg

Shows the ABS valve unit that has two or three connectors under the plastic cover. These are usually OK but you can take a look if you still have the light on. Note that there will probably be another large plastic cover all over the valve central, that you have to remove to see it. Then you need to remove the second smaller plastic cover that has ABS written on it. But do this at a last resort, the issues almost never come from this guy.

The ABS central unit is located under the carpet on the front right of the car (opposite to the battery).
I would really check the