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So on the way home yesterday, everything drove fine. Key fob in my pocket, door handle unlocks no problem, "dummy" entry and drive works no problem to start the car.

Drive home and go to turn the dummy key to the left for 2 seconds (normal) and it won't complete the "shutdown" (move column in and what not). Go to turn the dummy key back to START and it says NO KEY FOUND.

try to lock and unlock with the handles, nothing. The key fob BUTTONS work to lock and unlock....but the proximity sensors on the handles do not.

To start the car now i can no longer use the entry and drive feature.....it requires the use of the key in the fob.

Three questions to start the discussion:

1. Why does the fob key work to start the car, and why do the buttons works, but nothing else?

2. Considering EVERYTHING no longer works, is it safe to assume the Kessy module?

3. Is there a fuse location i could check to see maybe the Kessy is not powered?

I don't have any sort of diagnostics, which i know will make it difficult to diagnose. But last resort will be to bring to and Indy shop with the porsche programmer.


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loren, Do you have a wiring diagram of the two plugs on the module? it would be easy to diagnose if i had the diagram to scope the various inputs and outputs of the module.

How does the ignition portion work? When i use the key fob key, is it just using a mechanical lock tumbler to allow the ignition to work? Or is it still using a sensor to read the key that is being inserted into the tumbler.

I find it interesting that everything stopped working at once.....meaning it must be a common issue i the Kessy Module.

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To my knowledge, there are no published diagnostics for this module other than through the Durametric system or the PIWIS, so I am not sure you will get anywhere testing inputs and outputs as there are alot of CAN bus communications involved...........

On the Kessy system, you have 3 interior antennas, and 6 exterior antennas. All four door handles have an antenna in them, and the rear bumper has two.

Communication path for Keyless Entry - Opening VehicleTouching the door handle (proximity sensor) leads to sending a key query signal in the area of the vehcleProximity sensor in door handle detects a hand touching it and sends a wake-up signal on the line between the door handle and the Kessy/Immobilzer control unit. Kessy activates a search for a valid key in the area via the integrated antenna in the door handle. The carrier signal is a 125 KHz field that is brodcast by the door handle antenna. The search signal is modulated on this signal. The search takes place only on the side of the vehicle that the wake-up-signal was triggerd on.The key transmitter answers the query from the Kessy using the alarm radio frequencythe key receives the 125KHz transmitted, evaluates the signal and sends a corresponding answer using the alarm remote frequency (315 MHz, USA market) A normal 125KHz signal without the correct requesting vehicle information will not wake up the key; this reduces the quiescent current draw of the key.The vehicle receives the alarm remote key signal through the alarm remote antenna in the rear spoiler.The signal sent by the key received and evaluated by the kessy through the alarm remote antenna in the rear spoiler. The answer from the key contains a vehicle specific data so that only keys assigned to the vehicles kessy control module are woken up and this after the vehicle implemented wake up.The Kessy evaluates the key data and commands the central locking system to unlock via the rear control module.The communication between the kessey and the Rear control unit is via the comfort CAN bus.Communication path for Keyless Entry- Starting VehicleConfrimation within the igniton switch starts the search for a key within the vehicleWhen the ignition key is inserted in the ignition switch and rotated the "S" circuit is actuated and the switch position is detected (KL15, KL50,) This initiates a search for a transponder in the interior of the vehicle. The search takes place at the same time on the outside of the vehicle by the interior antennas.The key answers the control midule request on the alarm remote radio frequencyThe key receives the 125KHz signal, evaluates this and sends an appropriate response via the alarm remote frequency 315 MHz.The vehicle receives the signal sent by the Kessy and releases the steering lock and enables starting in the DME and KESSY.The signal sent by the key is received by the kessy and evaluated. If the key is confirmed as assigned to the vehicle the starter operation is allowed and DME enable signal (via CAN) is sent. The starter engages and the engine starts.Communication path for keyless entry-Leaving VehicleOperation of the door handle micro switch leads to a key query being sent to the outside area of the vehicleThe micro switch is hardwired to the door control module and the door opening signal is sent to the kessy via the Comfort CAN. The kessy initiates a search for a valid key in the exterior area of the vehicle via the antennas that are intergrated in the door handles.The kessy evaluated the key data and controls the central locking system via the rear control module. The key data is evaluated in the kessy and then a command to lock the vehicle and actuate the alarm function is sent via the Comfort CAN.

See? All very simple...............

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