ScottR

Morning all

Two warning lights came on this morning and with no manual to hand I can't recall what they mean but more importantly are they serious and should I drive home!

Warnings are:

No 13 - the pic of the 4 wheels and transaxle - like the lock diff picture
No 8 - (!)

Pic attached - I have red squared the two that came on (ignore the orange circle as I found this pic for reference)

Help please!

Scott

Computamedic

The two lights are PDAS (the 4WD system) and the brake pressure warning light. Since the PDAS systems is dependent on the high pressure hydraulics it's likely that you might have an issue with the fluid level, the hydraulic pump or the pressure switch attached to it.

Normally on a C4 the lights will stay on until the pump has achieved the required pressure. You can usually hear the pump running when you first turn on the ignition and it will usually stop after a minute or so. If it doesn't stop after two minutes there is a danger the pump will overheat and cause more damage.

You didn't mention the circumstances when the lights came on. Engine running or not?? Driving or parked?? I would be careful about driving until you identify the problem. It may be something simple but it could affect the braking.

Regards

Dave

DaveK

These lights can stay on if you've got the known problem with the clock solder joints (in which case getting the revs up a bit usually clears them). Do a search for more info.

Rocket Rob

Agree with the above, also check that your brake fluid reservoir is completely full. I have had error lights if it isn't.

ScottR

Thanks - I will check the brake fluid level first.

The lights came on after about 20 miles of driving. I was on the motorway doing about 70mph. Pulled over to the hard shoulder, switched the engine off and back on again and the lights had gone off. So carried on driving and they came back on again after 2 or 3 minutes.

The lights normally stay on when I first start the car for about 20 secs or so and then go off - presumeably it's taking this time to pressurise? Is this normal?

Rocket Rob

Yes, its normal for the lights be on when you first start the car. They should last about 20-30 seconds. Yes, its while the system pressurizes.

Good luck in isolating the problem. I hope its something simple like low brake fluid level.

DaveK

Coming on after 20 mins driving does sound like a different problem from the other suggestions. Fluid level is the most likely cause I think.

Computamedic

Scott,

Although your description is a little different to the problem I had (I had the ABS and PDAS lights while driving) there is a chance that the cause may be similar.

It took more than a year of changing bits to eventually home in on the problem my car was experiencing - and it turned out to be nothing to do with ABS or PDAS!! The root cause of the problem was HT leakage from poorly insulated distributor caps and coils. Fortunately it was spotted by a very experienced Porsche indie and since replacing the distributor caps and coils the problem has never re-occurred in more than 3 years.

Don't always assume that warning lights only relate to the systems they monitor. Sometimes Porsche diagnosis needs some lateral thinking!!! Hope that helps.

BTW, the bad solder connections in the clock that Dave mentioned often causes the charging circuit to malfunction and the charge light will often not extinguish until you rev the engine over 3,000 rpm. This can affect the voltage in the system and, hence the ABS and PDAS systems which are particularly voltage sensitive.

Regards

Dave

ScottR

Cheers Dave.

Well, I checked the brake fluid before setting off for home - absolutely fine, on the max mark. Started the car, the lights went off after about 20 seconds as normal and I then drove home the 40 miles with no bother at all.

So, not sure how to proceed on this one.

ScottR

Most odd - the lights came on again this morning after 8 miles.

I hate intermittent problems!

Brake fluid is at max. Any advice on what I can check first without spending lots of money?

Scott

Computamedic

Scott,

Pop the caps off the distributors and have a look inside for corrosion and evidence of arcing. I bet you'll find lots of evidence there and I bet you'll find that replacing the caps and rotors (and coils if necessary) that your problem will disappear.

Have a look here to see what mine looked like.

Regards

Dave

Wachuko

What you have is what we call here the x-mas effect... and the source could be one (or several) things. None of them are going to leave you stranded.

It could be coils going bad, distributor caps and rotors, plug wires arching, a bad or low battery...

Start with the easy stuff... clean and fully charge the battery. At night, raise the hood and with the engine running, spray a mist of water over the plug cables. If you see sparks you will know the wires are in for a change. Check the caps for cracks (or just replace them along with the rotors).

I really do not think this has to do with anything on the ABS or AWD system... when that goes bad you will know... back in June 8, 2000 I was using the car and had to make a sudden stop
at a speed bump. The ABS came to play. Since it was the first time I had sense the system in action I decided to give it another try. It worked flawlessly. Close to my house I made a normal stop and to my surprise the brake pedal would not respond. I had to push it extremly hard to make the car stop.

The problem was solved by: Pressure Sensor replaced(US$247.55 - Part # 964-606-904-00), Relay replaced (US$33.81 Part # 964-615-135-00), Rubber O-Ring replaced(US$4.99 Part # 999-707-094-40). Labor US$147.90 Minus PCA discount.

And you have nothing like that... so keep using the car, don't worry about it. Just make sure you do all these tests and start replacing those that you see are in need of attention.

Here is a thread of when I did the install of new cables, coils, etc...

Changing Spark Plug Cables

ScottR

Cool, thanks guys - I shall check these things out over the weekend.

A couple of other things that are maybe worth mentioning are:

1) my ABS works intermittently - no warning lights, it just works once and then the next stamp on the brakes it doesn't. I did post about this when I first got the car but spent too much to no avail so just drive the car assuming no ABS now (ABS post)

2) My spolier warning light sometimes stays on, even though it operates fine. Soemone once mentioned this could be moisture getting into connections. My boot seal probably needs a good clean or even replacing so it could sometimes be a little humid in there.

Just thought I'd mention in case there is a link at all. If not, then I'll carry pursue these problems separately!

Scott

grankin

The warning light at bottom left (on a C2) is what the manual (I did RTFM!) says is a pad wear warning. Mine now comes on after putting the car through a car wash. Goes out sometime random time later. Sometimes (now) goes on randomly, then goes out later. Plenty of fluid, plenty of brakes. Mechanic says the sensor sometimes gets damp ...

jembolt

Your symptoms are exactly the same as mine were, solved by replacing the plug wires. It took a bit of trial and error to get there, though.