Help - 996 door locking and frunk light issues

[Jim Doe]

I have a 2001 996, original owner, no water issues, parts are all original.  Car sits unlocked in garage.  Recently starting getting a double horn signal every now and then.  Would also hear locks buzz every now and then on their own.  Also noticed the frunk light going on and off on its own at some stage. 

 

Read codes using Durametric and am seeing:

61 - central locking limit position unlock not reach

Status: Present

Occurrence Counter:24

47 - central locking synchronization

Status: not present

Occurrence counter: 15

 

When this problem started, I noticed that the passenger door would not lock (using key in driver’s door including using the emergency locking operation of turning key to lock position 3 times in succession or a single turn) or using the fob.  Both driver and passenger window would drop fine when using the relevant door handles.  Battery is fully charged.  Car runs fine.  No blown fuses.

 

So reading all the posts about failing microswitches, I removed the passenger side lock assembly which is what I originally suspected to be the problem.  Took it apart and redid all solder connections on the PCB and then did a temporary reconnect of just the electrical side of the lock module with the cover open so I could see what was going on with it and why I would only hear a buzzing sound rather than the definitive click from the passenger lock.  The passenger lock assembly just has 2 microswitches (one outside the assembly to tell if door is closed and the other inside that gets actuated by a white plastic ramp that is driven by the single motor). 

 

The buzzing sound was because the motor would turn but the black clutch type mechanism would not turn and hence the lock would not change position.  See attached video.  The sound that the locks make can also be heard here.

 

So I tried applying about 3VDC to pins 1 and 2 on the removed passenger door lock using a bench power supply and I could get it to work just fine and change directions.  Both microswitches tested just fine and were clean.

 

Somewhere along the way of all of this troubleshooting, the driver side door lock started doing the same thing and making the same sound.  I have not taken this apart as I am guessing it is perhaps the same situation as the passenger one that I have removed.

 

I have removed the central locking switch and that tested ok.  I have tested continuity across the frunk microswitch by disconnecting the connector in the frunk and manually closing and opening the latch using a screwdriver while checking continuity and it works fine.  Reason I was looking into this as one other weirdness that started at around the same time is the frunk light (original non LED and bulb is ok) would come on and go off on its own and now does not come on at all.  It has +12VDC going to it but the - is not happening which happens through the alarm module I believe.  I do have the alarm horn disconnected currently as I got tired of hearing the double horn signal and hopefully that is not causing any of these issues.

 

The gas cap locking pin also does not not move.  I tried manually pulling and retracting it and it moves manually like that but not when locking or unlocking.

 

Also removed the alarm module from under the driver’s seat.  The fuse was fine and both sides of the PCB visually looked ok.

 

So my questions are:

 

-Could both my locks have failed one right after the other where the lock motors are not working properly and that is the only problem?

 

-Or is there something in the alarm module that has failed?   The weirdness with the frunk light along with the locks not working despite microswitches being okay is making me wonder if it is indeed the alarm module.

 

-Anything else I can try to narrow this down?

 

Thanks.

[Loren]

 

How old is your battery - if it is 4 or more years old replace it.

A weak battery causes all kinds if electrical anomalies.

 

Since you had the door locks apart - did you inspect the mechanical levers for wear or cracks? - they can wear out and the car is 22 years old. 

[Jim Doe]

Thanks for the reply Loren.  The battery is under a year old.  I charged it recently just to rule that out as well.  The car has under 50K miles and even though it is 22 years old, it has not been driven much (which I realize can be a problem as well with some things).  The passenger door lock levers look fine.  Even with only the electrical portion of the the passenger door lock connected to the car temporarily, I cannot get it to actuate properly between the locked and unlocked states.  I was planning on getting a new passenger door lock to rule that out as that is less expensive than replacing the alarm module. 

 

I did continuity checks from the relevant terminals on the alarm module to the passenger door lock connector pins 1 and 2 and measure 5 ohms because the driver lock is still installed and is in parallel.  I am sure the wiring is all good.

 

I forgot to mention in my original post, Durametric has been a little iffy with the alarm module.  I had to revert to version 6.3.1.7 in order to view error codes and clear them.  However even this version shows all the inputs as being open and regularly freezes up when showing input signal status.  The activations all result in the door lock buzzing sound.  Reached out to Durametric and they said they had issues communicating with the alarm module on this model so I assumed that the issues with Durametric were all software issues but am not sure.

[Jim Doe]

Hi Loren,

 

I replaced both passenger and driver door locks with new original Porsche locks and am sadly in exactly the same state as before where:

Windows drop fine when relevant inside or outside door handle is pulled

I still can only lock the driver side lock and only when using the key

I cannot lock or unlock the doors using the fob but can release the frunk using it.  Attempting to use the fob to lock the doors results in a buzzing sound which is is probably an attempt to lock followed by an instant unlock.

 

Is there some sort of magical sequence to reconnect the fob with the alarm module?

 

My symptoms seem identical to this post:

https://www.renntech.org/topic/38717-door-locking-problems/

 

Back then one of the things you had suggested was to have the alarm module reprogrammed.  Can you please provide more details on what that means and what is required to do this?  This is the original alarm module and there is no water damage.

[Loren]

You will need a Porsche PIWIS tester ($18,000/year to lease) and your cars IPAS codes (from a dealer).

Or a shop with a PIWIS should be able to do that also.

[Jim Doe]

Thanks Loren. Will update on how this goes.

[Haiyan]

Assuming that the central lock switch + door locks + wiring harness are good, then you need to recode/reprogram the alarm unit via a Porsche tester it's the only tool that will be able to do the coding feature don't waste your money on aftermarket tools, also the IPAS codes are not needed when recoding/reprogramming the alarm unit as long as the unit is not replaced.

 

Coding is straight forward thing and it takes less then a minute to do:

1- Insert the Porsche tester and turn the ignition on

2- choose alarm module then click Coding/Programming tab 

3- Under "Country Coding" choose the correct country code.

4- Write the coding via the tester, after the coding is done and completed.

5- switch off ignition and remove key

6- switch ignition again and clear codes and you are good to go

 

Note: sometimes a different country code will work with you even if your car has a different code.

 

 

 

 

Edited June 14, 2023 by Haiyan

[Jim Doe]

Thanks very much for your detailed response Haiyan.  I was able to connect to the alarm module using PIWIS2.  The car is a 2001 996 and a US model.  PIWIS reports the alarm system as being an I48. 

 

When I checked coding, it just said ---

 

I changed it to USA as it is not a convertible (and I can confirm that I did not need to enter any special codes to do this)

 

The only fault code I get is 61: central locking limit position safe lock not reached, switch position implausible 

 

I am able to clear the code but still unable to lock doors.  I hear them attempt to lock but nothing happens.

Using PIWIS drive links I was able to test that I could lock the fuel cap door but was not sure how to unlock it so just manually pushed the locking pin back as I did this test with the flap open.  I could also actuate the turn indicator signals.  I did not test locking the doors as based on another other post, I saw they might stay locked and be problematic to unlock without applying voltage to the locks from the connector.

I then monitored the input signals.  I saw both doors being closed and locked which was not the case and opening or closing the doors would not result in a change in state from closed even though the relevant window would drop when the doors were open and go up when they were closed indicating the microswitches were fine (I replaced both locks with new Porsche locks).  So this would perhaps explain the code 61 as the alarm system is seeing the doors as being  closed and locked and also not changing state when trying to unlock.  Additionally the frunk and engine compartment lights stopped working (flickering initially and then stopping totally) when the initial door locking issues started a couple of months back.  The alarm system also sees the front luggage compartment and the rear luggage compartment/engine compartments as being closed when they are not and opening or closing does not result in a change in state.  This would explain why the lights do not turn on either because it only sees them as being closed.

The only inputs that I could get the state to change and display correctly in PIWIS were:

Buttons 1 and 2 on transmitters (change from not actuated to actuated when the relevant button on the fob is pressed)

Central locking system button which changes between not actuated and (close) actuated or (open) actuated

Front lid release and read lid release buttons both work and updated correctly

With the key in the driver side door lock, the door lock barrel signal changes between not actuated to (close) actuated or (open) actuated.

Again there has never been any water damage with the M535 alarm module.  I have resoldered all through hole connections on both connectors where they connect to the PCB as well as all through hole components such as the relays.  I have replaced the electrolytic capacitor.  Inspected all surface mount components with a microscope and do not see any bad solder joints.  All fuses in car and the one on the alarm module are good.

I had issues with my ignition switch where it would not release the key and so had replaced it with a Uro one last year and have not had any problems with that since.  Battery is 1 year old and been recently charged as well.

Anything else I could be missing in terms of some ground or supply signal to the alarm module?  Or has something failed on the alarm module?  After replacing my locks which it now turns out was not necessary, looks like my next step is to have the alarm module replaced.

 

Thanks.

 

[Jim Doe]

Should the M535 alarm module (996.618.262.01) in a 2001 996 report in PIWIS2 as an I32 or I48 module?  Since mine is showing in the control module list as an I48 and not an I32, could that explain why many of the input states are reporting incorrectly?  Is there some way that something has got mixed up some place that is making it report as an I48 rather than an I32?  Or is it indeed an I48?  The photo below shows the top of the module.  For FKW it says 48/00 and for LNR: 0132.  

 

[Loren]

MY2001 and newer need 996 618 262 03.

[Jim Doe]

Thanks Loren.  I had learned that 996 618 262 03 is the current part number for the alarm module for my 2001 996 as well.  The original one in there is a 996 618 262 01.  I was just surprised that PIWIS indicates my original ones as being an I48 which is supposed to have more features than the more common I32.

[Jim Doe]

Got a new alarm module installed and door locks and fuel cap are locking fine again and the frunk light works fine too.  So this was a strange failure mode of the alarm module where certain input signals i.e. both door closed and locked states as well as frunk close state were reading incorrectly but am glad it is finally resolved.  This also means my original door locks were absolutely fine.  Thanks all for your help and advice through this one.

[Loren]

[emflo88]

Hi Jim, I am having almost the exact same symptoms as you reported here.

Since it seems that replacing the Alarm Module did it for you can you share the part number(s) that you used ?

I have a 2002 996 Targa so I can find the equivalent part for my model if its different.

thanks

[Jim Doe]

On 2/12/2024 at 9:24 PM, emflo88 said:

Hi Jim, I am having almost the exact same symptoms as you reported here.

Since it seems that replacing the Alarm Module did it for you can you share the part number(s) that you used ?

I have a 2002 996 Targa so I can find the equivalent part for my model if its different.

thanks

Just saw your post EmFlo88.  The PN of my original alarm board was 996.618.262.01.  The new alarm board that was installed has a PN of 996 618 262 03.  Good luck with getting it sorted.  It was a real pain.

[emflo88]

Thanks Jim. Just looked it up and that’s a very expensive part so I think I’ll try something else first