2000 996 C2 - ABS Light Constant - Can't Read Fault Codes

Hi Folks, Been awhile! I'm trying to fix the ABS fault on my 2000 996 C2. It started off with an intermittent ABS light that would go away after being driven for a few miles. Now it is on constantly as soon as the ignition is switched on and will not go out. I've tried the following fault code readers and both of them claim that they are unable to talk to the ABS ECU - Durametric (Enthusiast version) - selecting ABS 5.3 iCarSoft POR II "Fault in communication with vehicle ECU. Please confirm 1. This vehicle is equipped with the system: 2. This system is an electrical control system. 3. The diagnostic connector is OK; 4. The ignition is switched on." I also needed to reset the airbag warning light after dismantling the door panels. The Durametric did this with no problems so the diagnostic connector appears to be working. For some reason though I can't communicate with the ABS unit. I've disconnected and reconnected the ABS ECU wiring harness and also checked the fuse in the main fuse box which was OK. Has anyone else seen this problem? Is this something to do with the early cars? EDIT: Think I've found the answer, looks like the iCarSoft POR II doesn't support ABS on the 996! So will have to return it. Apparently the POR V1.0 and the POR V2.0 do support ABS on the 996. Foxwell NT510 also reported to work... Thanks David :thumb:

Looks like you have found an answer..... Not sure where you are based, however I have the Foxwell NT520, I also have a high-end Snap-on unit, if you wanted to try them (Am South-Bedfordshire). Based on recent experience with a different manufacturer (Honda), the Foxwell struggled to reliably connect to the ABS module (I had the Honda specific Foxwell software). The Snap-on had 100% relability and was a life-saver. Hope you find your issue. If its been an intermittent thing, thats now become permanent am guessing it could be wheel-speed sensor issue - thats been the case on lots of my cars in the past.

Thanks for the offer - I'm near Worcester in the Midlands. Well I got the multimeter out today and using the guide in the workshop manual I was able to find the fault with the ABS... Right Rear wiring loom for the ABS and Brake Pad Wear sensors has a big slit in it! Porsche want £115 for a repair section!!!! Maybe I can cut it solder the individual cables and heatshrink them all - what do you folks think? Seems ludicrous charging over £100 for a repair cable...

Sorry i missed this first time around .. also that brake pipe needs some wax oil on it .. The issue with the repair .. that outer rubber casing is strong and tight .. you would need to cut it back each side with a blade to expose the wires .. go gentle but firm with a stanley blade basically to open it up . You can then repair as needed .. soldering obviously .. downside is .. resealing ( possible water ingress ) and the solder makes that section inflexible .. in other words the repair might not last over time . yes you can .. i have considered it in the past and if it was my car i would if only as a temp .. see how it goes type of fix . ref ABS faults going forward ... if the light comes on as soon as the ignition is turned on then there is a short in a sensor or wiring as it fails the self test . If the light comes on above say 10 mph or during a journey then it can be a sensor or reluctor ring as the car is looking long term at the signals from each wheel and either seeing a random drop out or a weak / corrupt signal .. At that point it says .. ok i cant trust you .. your a safety item so im shutting down . ABS light on = No Abs .

Hey demort - hope you are well mate? Precisely how I'm thinking :thumb: Temporary repair so I can get out and enjoy the car again now that the weather is improving. I will monitor the situation and may have to dent the wallet in future to fix it with the repair cable from Porsche.

All good young man but totally snowed under with work atm .. im even bringing it home with me to try and figure out issues ! Trying to keep up with questions here but it's a struggle atm hence i miss some like yours . Temp repair will do just fine .. it may well last several years .. at the end of the day it's a wire that joins one component to another .. my main concern .. Soldering a wire connection .. you will end up with about 1 cm of rigid wire that if flexed as will happen with this loom will end up snapping . All i can say is we fit the repair kit .. and be thankful Porsche sell this as opposed to normally just saying you need the entire loom !!!!

Good to hear you are well - I don't know how you find the time to duck in hear and answer our queries as well as doing your own work! :worship: Bad news - I started peeling back the outer sheath, found that only one of the wires was completely worn through. The problem though is the core is corroded, even after cutting back the faulty wire 20-30cm I couldn't find any good internal wire core. Question on the repair sections - I see there are different part numbers for the f/l, f/r, r/l and r/r. I'm assuming the only difference is the length of cable as looking at a f/r repair section it looks identical. They must be the same internally as they are feeding back the abs sensor and brake pad wear sensor signal at each wheel. Thanks - :thumb:

I do my best and that has just reminded me .. i need to figure out the resistance values for a 2013 cayenne throttle pedal .. twin potentiometers but i don't know the exact workings and i have an issue with one at work lol . On that next i guess .. water and wiring .. the pain of my life .. like you i work on older cars which were never designed to have water proof wiring .. once it goes black it basically can't be soldered .. I have in the past scraped off the corrosion and attempted a solder connection but so much heat and flux is required that you just tend to melt the insulation for an inch or so each side . I will say an old fashion crimp connection works but obviously not for something like this ... early 911 with say a light not working and you can do this .. won't last long term though . The repair looms .. they will be different sizes depending on the corner but all do the same thing .. i seem to remember that the o/s/f is the more common one to need to replace . Best way .. phone an OPC parts dept .. i doubt you will get one anywhere else .. maybe but i doubt it .. give them the chassis number and they will look it up .. cost , availability and part number if needed . Fitting it is no big deal .. just follow the loom and cut it in where you wish .

i've just completed my research on my pedal issue .. i know it's of no use , i know no one cares but i felt id just share .. in a hidden corner of this forum what i have just posted to my boss in relation to this fault .. this is unpaid overtime if you like lol . Just ignore it basically as im happy ... i have a path to fault find next week ... some jobs are a bitch to find ... this is one and there is no way we can charge the hours spent finding the issue .. That is the downside of Diagnostics and why garages don't really want to get involved ... i kid you not . Images attached are what I've found in our manuals .. The voltage for P1 should be around 1 v .. i think this is on the low side but the issue with P2 masks this as it throws a fault as soon as the pedal is touched .. in essence we have an issue with the voltages for both pedal potentiometers i feel ... that might lead us to a rail 5 volt feed issue .. needs checking .. if there was a short between the wiring signal of P1 / P2 then the voltages would be similar which they are not .. P2 at idle seems to have about the correct voltage as does P1 ( need to confirm that ) .. once the pedal is moved we have a fault code and the system shuts down .. its not seeing the voltage increase at the same time as P1 basically .. again a short on P2 signal wire to any other would flag a code straight away so i don't feel this is a wiring short atm .. need to confirm that though . A wiring test , continuity and a test for P2 signal wire short to any of the pedal wires is in order but I'm leaning towards this is a DME fault or a rail / sensor overload fault atm .. that's going to be a pain to diagnose as its every 5 V sensor disconnected and we have no access to half of them without stripping items to get access . If its a DME that's at fault .. how the hell !!! iain.

demort I think you got the wrong thread? :?: Anyway thanks for pointing out the corrosion on the brake lines, I tidied them up with a brass brush and put some Bilt Hamber Dynax S50 on them. My repair cable also arrived today so I can patch the cable tomorrow hopefully! Bit of a faff to get enough access to fold over the rear carpet and get to the cable where it enters the car!

All fixed and the ABS light went out straight away! Brake pad light came on though as one of the crimps pulled out from the heat of the heat gun! :hand: Then both were fixed and all was good with the world :grin: