screamingflat6

Hi,

I have been medalling with the car and its gone wrong for me.
The abs and four wheel drive lights have been coming on and off for a short while.
So reading on here as much as I could I went for the easy fix first, the brake pressure switch.
I went to my porsche mechanic mate and this is what we did!

1,took the two connectors electrical off the brake booster pump
2,took the earth off the battery
3,released the pump from the body work
4,then released the fluid in and out connector on the brake booster unit.
5,My mate pumped the brake pedal in the car twice?
6,replaced the switch
7,put it all back together again

I have checked fuse 15 and the relay with others for my 965 all good.
I have lost four wheel drive and cannot hear the booster pump working no power brakes,just heavy as hell pedal!!
I think my system needs bleeding and its gone into a fault mode
What do you think I have done?

Many thanks,Gaz

Indycam

When you say you have lost 4 wheel drive I guess you are saying the "lock up" switch does not work to lock up the 4 wheels .
You have no hydraulic pressure because the hydraulic pump is not running from the sounds of it .
The new switch you put in may be bad .

screamingflat6

Yes,

The problem started with two bloody lights in the car getting on my nerves,so bought from the porsche dealer a new switch.
Did everything as stated,now its more trouble.
The switch on the centre consul is not lighting up when selecting diff lock and when I use to start her up I would hear the pressure building up in the system ie the pump pumping.
Heavy pedal, on the brakes. going home through the traffic was scary and risky.
The Switch was a NIB ate genuine dealer part.

I have caps, rotor arms, and leads to get the frigging lights out!!!!

I just couldn't have been lucky with a simple switch change could I.

Thanks Gaz,

Computamedic

It sounds as though the first thing you should do is a full bleed of the primary hydraulic system, including the "bomb". The purpose of the pressure switch on the pump is to turn the pump off once the required pressure is reached. If the pump doesn't start it suggests that either the switch is open circuit or there is something else wrong with providing power to the pump.

BTW, pressing the brake pedal will achieve nothing other than potentially create a problem. The hydraulic system powered by the pump is not part of the brake system directly, it's used for assistance as well as to operate the PDAS system. The system needs to be bled with a pressure bleeder.

Regards

Dave

Rally Guy

Further - it is entirely possible that your "NIB" switch is indeed bad. I've had a number of "new" parts be DOA despite also being "NIB"!

If a full, proper, succesful bleed doesn't sort things - I'd check that switch.

Don't beat yourself up over this - just think of your current state as being 3/4's of the way through the fix - you're just not quite finished. ; )

RK

screamingflat6

Hi, Dave

I have put my number 51 relay out of my turbo in, no change ,also checked fuse 15 good.
I will get my old switch back in the morning from my mate and then see another mate who is porsche trained and see if he can put it on the hammer and bleed the system for me.

Regards Gaz,

Indycam

How can you do a bleed if the pump does not run ?

screamingflat6

Indycam,

I am with your original post,all was well until the new switch was installed.

I think its a duffer,all the powered side of the car is ok, the fuse and relay have been tested and are ok.

I'm getting my old switch back in the morning and returning the new one back to porsche.

I think I want the system on the computer to see if I need to address any other issues as I want the car right.

Regards Gaz,

Indycam

The switch might be good and the wires to it bad / broken .
Do some tests to try and find where the fault is before replacing parts .
If you can get the pump to run by jumping the contacts at the switch connector ...
And so on .

screamingflat6

Good afternoon all,

I have put the old switch back in the booster pump and we have power assisted brakes again.
Took the switch back to the dealer who was pi**ed on the return of the part.
I have now got another switch on order, but they want the switch that was returned to be tested before they will believe what I am telling them.
The dealer offered me a cheapish price to plug my targa in on their computer while I was there and run a diagnosis check.
It was crap, "all systems ok except we cannot find the abs system" is what the technician told me.
This light thing started last year and was a intermittent problem, now they stay on
Do you think a relay could cause this 51 is ok, but is there another relay working with 51 on the abs or four wheel drive that could cause this headache for me.

Gaz,,,with brakes and two lovely red lights.

boxsey911

If it was just the ABS light I would do the following in order:

1. Check the battery is putting out the right voltage (i.e. it's in good shape).
2. Clean the positive battery terminal leads with grit paper (especially the tail lead that goes to the ABS controller).
3. Unplug the ABS lead from the controller, clean up all the pins as best you can and re-seat it firmly (hold the silver clip up when you re-seat the plug).
4. Check all four wheel speed sensors for breaks in the cables and take them out and clean them up.

NB. I'm ignoring the 4WD light because I have no experience of it but maybe that light is linked to your ABS problems.

screamingflat6

Boxsey

Thanks for the cake at Oulton very nice indeed.

I will get my reading head on tomorrow afternoon and get amongst Adrian's book of repairs.
I think the idea of cleaning the earths and connections to the units is good, I will look at trying to do this tomorrow afternoon after reading Adrian's book.
I have had a new bosch battery so voltage is good I have bought rotor arms a pair of dissy caps also to try and stop this.
It's not stopping me going this sunday on John's evo triangle run,but I will get them out in the end, the lights that is.

Gaz.

Sten

Gaz,

You have a pm, although I hadn't seen this post. The hammer will not communicate with the older version of the PDAS 'Brain' p/n 964.618.126.00 to read faults, but it will bleed the diff locks. Do the warning lights come on straight away, or once you've moved off? Likely suspects assuming all connections, earths etc are OK, are stuck accelerometer(s), interlock and/or ABS relays. I have some spares...

Regards,

Baz

Pesty

Could this be the dreded corrosion of that conector into the ABS controler? i'm scared to remove mine in case it disintergrates

screamingflat6

Woke early today,,

The fault is doing my head in!
So today I got positive and very brave.
I rang a guy who's a bit of a wizz with the abs etc and he kept telling me about the £2500 pound abs computer corrosion problem, so as you can imagine I was starting to get negative again.
So I took the bull by the horns and yes I pulled the plug on the computer I was so scared that the thing would be wrecked and a mass of corrosion in my hands.
Good news is its ok, I have split the case and its in with my socks and vests in the airing cupboard for a couple of days I couldn't see any water or corrosion stains or smell any buring etc inside the case.
I will buy some contact cleaner tomorrow and only apply it to the push in plugs I have been warned not to clean the computer inside.

Thanks to everyone for ideas on the fix , I will fix this car