Central Locking - new angle

My remote (fob) central locking release and immobiliser cancel does not work. Meaning manual unlocking followed by a fast key insertion into the ignition switch to turn the ignition on before the alarm goes off. The central locking system works on both doors without the remote from the dash button, once I am in the car. The OPC tried a new key head today and coded it into the system. No good. So it seems it is the module in the ECU or the aerial. Is this correct? And where can this latest exploration lead? I believe I have read almost every previous post on this topic and trired all the usual tricks. Many thanks

Interesting .. very interesting .. First off there must be a good Indy local to you , far cheaper labor rates and far better on 996 faults then OPC,s these days .. not having a go at OPC but they tend to work on cars upto 6 years and unless there's an old guy there they will struggle with faults like this . The car locks and unlocks from the key i take it .. car locks and unlocks from the dash button .. It's only the fob that it doesn't work from .. im also assuming it has been correctly coded on and is not an old unit .. a fob once coded to a car will never work with any other car again .. its junk , again if the number we enter has been put in incorrectly .. it's a long Hexadecimal number then it will never work . let's break this down ... manual key is an override system .. it will bypass a fault ... Dash button .. well the car will let you lock the car from inside with the keys in the ignition .. The Fob however will not lock the car if it thinks the keys are in the ignition !! safety feature .. On the alarm control unit values when using a tester there is one section thats says .. i think ... as i'm not at work to confirm the actual number but .. Term 56S .. this is what tells the alarm system whether the keys are in the ignition or not... the ignition lock can go faulty and think the keys are inserted when they are not and the fob will not work . Tester on the car , look at the values and if it doesnt change to no 56S when keys are removed then you need a new ignition lock . Moving on to what they have said .. if the alarm control unit has been wet ( under the passenger seat ) then it can cause all sorts of issues .. i've replaced countless ones over the years but never for this fault . The aerial .. its part of the wiring harness and if unplugged then the fob should still work if very close the the CU ... visual check .. is it unplugged . I would humbly suggest print this out .. probably minus the OPC comments and give it to the service advisor .. No guarantee that i'm right its only to say i've seen it before .. it took me a day to figure it out and it was term 56 S and a new ignition lock required . Again im not 100% sure its called term 56s but there is only one line with this figure be it 54 or 56 . EDIT .. I forgot to add .. when using a tester on actual values you can see when a fob button is pressed .. 1-3 buttons so it's easy enough to check if the aerial and cu are receiving the fob signal .. in this case it's back to the CU not reacting to the signal as it sees something it doesn't like .. ignition lock fault perhaps .

Thanks for all this detail deMort. Yes the car locks and unlocks from the key when inserted in the door. And from the dash button (with when the car is unlocked and key inserted in IGN). They tried a new key from their stock and coded that to pair with the central locking system - no fault codes on locks or elsewhere - and still no go. They think they need to check the unit (which unit?) under the passenger seat and the aerial. Interesting about the ignition switch. I do have a local Indy I can try. The unit under the seat has never been wet to my knowledge, but I can pull the seat and have look around. Any images or diagrams around of the unit and its aerial around that you know of? Merv

Jon at JMG seems to be an authority on 996 keys etc, if you send him the alarm module and key he might be able to sort it - but again email or call him first and he can probably give you some insight into what the problem might be and what the solution might be

Many thanks but they are a long way from Australia. Merv

The alarm control unit is a large black box under the passenger seat , sometimes there will be a smaller tilt sensor box next to it .. RHD Alarm control unit is what has the key fob information in it .. the bit they have been coding the keys onto . The aerial is just a black wire going into this large box ... its either plugged in or not .. but if not then someone has unplugged it as they dont just fall out . Rule of thumb when diagnosing control units is try to eliminate everything else first .. the ignition lock has not been ruled out and is pretty easy to do so with a tester .... Yes it is Term 56S you need to check , i asked at work . Wet CU normally means a car that wont start or has central locking issues . Get your indy to read my comments then check the car .. we will see where we go from there

When I saw your user name, I instantly thought this bloke is Aussie, that make 5 of us from Gods country. If you're in Sydney, try Autohaus at Chatswood, they may be able to help :thumb:

You have made me wonder if it's my ignition that's at fault with mine. Usual thing everyone else has. Car does everything ok with key but does nothing from the fob. Interestingly just before I bought my car the ignition was replaced at Cavendish Porsche. I wonder if that has anything to do with it!!

To put it into perspective .. I've seen this fault once in 16 years .. i only remember it as it was a bitch to find .. i had wiring diagram sheets spread on the floor trying to figure this fault out .. routine stuff .. i forget .. the bitch jobs and i certainly remember them !! There will be no fault codes for this as it's not a fault .. the car is seeing the keys in the ignition so its normal as far as the car is concerned .. If you want to lock the car door with a second set of keys and keys in the ignition the car will not argue .. if you accidently press the fob button with the keys in the ignition then the car WILL not lock .. car locked with keys inside .. car won't allow that . It's a simple test but Term 56S on actual values on a tester must say inactive when the keys are removed ... The trouble i had back then .. i had no idea what Term 56S meant so i ignored it .. sigh .. i know now though ! Nothing to say this is the fault but its an item that we check .. along with key fob buttons shown as pressed when using a tester .. that proves the car can see the fob button signal .

Outstanding information thanks deMort. I will contact my local Indy on the IGN switch issue. Sounds a probability, especially as there are no fault codes yet found. I will also check the switch connections this weekend myself. I might also pull the passenger seat and have a look at the aerial and the area around the CL unit. Thanks also FZP. I am southern QLD and most pleased with my TT as it has only 50k kms and is in superb condition, aside from the pesky central locking.

The IGNition switch when pulled, 'looked' OK but I have ordered a scanner and will take the car to my local Indy, after pulling out the passenger seat and checking the aerial connection.

I'd be interested to hear if you've made any progress, as I appear to have exactly the same issue.

Mine also has the non-functional key fobs but otherwise works as expected. Both keys are original and worked at some stage. What I notice is that if I leave the key in the ignition and open the door, I get a message on the dash saying 'key in ignition' or some such. Is this a behaviour of the 996.2 only, or is it common the the earlier cars also? Basically, I'm wondering whether in deMort's scenario of the 56S condition, whether it would give the 'key in ignition' instrument cluster message? Because my keyfob buttons do not work, but the ignition switch seems to be 'self aware' if a key is left in.

No progress at this stage. Seems a common and annoying problem. The car is brilliant otherwise. I should have my scanner soon and that may help. School vacation here now and not much car action will be taking place. Yes I get the same 'key in the ignition" message if I open anything with the key in the switch. If that is normal, it and may eliminate the switch? I started to remove the passenger seat to check the CL aerial connections but ran out of time.

That message is interesting , im guessing its market dependant as it's not something i remember seeing before .. logically then with that message it cannot be the ignition lock faulty .. however i would still check it to be sure ... I looked on a car on friday .. it's actually term 86S for the ignition seeing the keys in the lock ( i was close working from memory after 7 years plus ) Don't forget though .. if it's not this find the value for key fob .. press the fob buttons and the tester will say if the car can see this signal .. if it can't then aerial ( i doubt ) or an issue with alarm cu ( again i doubt ) or the fob itself is not coded .