bigbuzuki

My KESSY decided to stop working today

I can start the car with the plastic control unit but cannot unlock or lock the car via any door handle/button.

Does anyone know how to get access to the KESSY control unit as I want to check out the connectors ?

Also the antenna locations for the KESSY would be appreciated.

Thanks.

crazywally123

I am having similar issues with my '03 Turbo. I am able to lock and unlock the front door via the door handle, but then I have to then open the door and manually unlock the rest of the doors. No other door handles are working. I am also no longer getting a horn when the doors lock. I am interested to hear what the responses may be to your post or if you get a dealer to fix it.

porsche52

Not a good idea, waste of time actually. But if you insist, the control unit is right above the accelerator pedal. Two connectors, one big, one small.

Its not a control unit. It is a black bit of plastic, thats it, no elctronics at all in the Dummy key. But, if you are able to start the car with the dummy key, then your interior antennas are ok.

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.
Do you have a new battery in the remote? The remote is not tucked away under your i-phone is it? You are not going to be able to diagnose the kessy system without a PIWIS tester, not gonna happen! So don't try.

Have you set your comfort settings via the instrument cluster. You should set all doors to unlock, you should also set for the car to flash and beep when locked, unlocked. If the vehicle will not retain its comfort settings, you will need a new rear comfort/doors control unit. They are junk and fail all the time. Dealer (or indy) will need to install this item too, as it requires the all mighty PIWIS tester to do it.

bigbuzuki

Great info P52!! Thanks.

Can you also tell us the location of the three internal antennae?

crazywally123

Thanks for the info porsche52! I tried to change the settings back, but as you mentioned they are not retained. I guess it's time to spend some money!

porsche52

One under the center console ashtray, under the rear cup holder in the center console and in the rear cargo area, I forget its exact location. If the car starts with the dummy key, then your internal antennas are fine.

porsche52

This is all the technical info one could ever need for the Kessy system. And go..

Communication path for Keyless Entry - Opening Vehicle

Touching the door handle (proximity sensor) leads to sending a key query signal in the area of the vehcle
Proximity 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 frequency
the 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 Vehicle

Confrimation within the igniton switch starts the search for a key within the vehicle
When 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 frequency
The 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 Vehicle

Operation of the door handle micro switch leads to a key query being sent to the outside area of the vehicle
The 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.

bigbuzuki

Excellent detailed post P52.

I also found a similar Kessy description previously but it was applicable to a Bentley, not Cayenne specific.

I am happy with the internal antennas as the car starts with the dummy key as you have stated.

As mentioned earlier I cannot lock or unlock from any door handle.
I should mention that I also don't have any unlock action from the rear tailgate open switch or the tailgate glass open switch when the vehicle is locked. Are these tailgate open switches hardwired, discrete inputs into the Rear control module?
If so this leads me into thinking that it could be the Rear control module at fault.

The dealership that is looking into this fault has ordered all the external antennas to be replaced as they had diagnostic faults of all the external antennas being shorted to ground.

I find it hard to believe that all my external antennas have all gone faulty at the same time.
Could it be a case of one faulty external antenna is dragging down the rest of the system?

Anyways, it's times like these I am happy that I have the CPO warranty.

Only hitch is that the antennas are not in stock here and have been ordered from Germany. (2-3 weeks delay)

Hope they fix the problem.

porsche52

Oh boy . It's a very good thing you have CPO and not paying for there on the job training.

Me too, no way in hell all the antennas are faulty all at the same time.
You have to think what do they all have in common? Ground points, etc.

One question for you. How many keys do you have for the car? Is there a spare key in the center console/glovebox? It is a long shot, but it is possible that the key that you always use and have on your person has a weak/dead battery and the exterior antennas never recieve the information from that key. But when you are inside the vehicle the interior antennas pick up the spare key in the car(with a good battery). Does the remote fucntion still work? Like I said, it is a long shot but I can see it occuring. If the remote batterys are dead, the keyless entry will not work.

The rear tailgate functions just like the other doors, except there is no proximity sensor in the handle. The rear hatch is hardwired to the rear control unit, when you press the button, it (kessy CU) searches the rear of the vehicle for a vaild key via the two antennas in the rear bumper. If the key is good, then the kessy control unit will command the rear control (via CAN) to open the rear hatch.

If I had to guess at what is wrong Id say the ground points for the antennas are corroded, possible internal kessy control module error. Or you have a strange remote issue like a stated above. But to think all 6 antennas are bad is crazy if you ask me.

Get out the

bigbuzuki

Thanks P52 - I do have 2 remotes and have changed the batteries on both.
I only ever travel with one xponder.
I tried both remotes individualy but still no go on the unlock/lock function.
Both transponders work ok when starting the car with the dummy key as well.
I am pretty certain that both remotes are fine.

I managed to get the Durametric tester hooked up today.
The only faults that were stored in the Kessy were as follows:

code 181 : Antennas on rear bumber - Short to Ground or Positive Present.
This sound like the cause of my rear tailgate/hatch not opening as you mentioned.

code 183 : Interior antenna - Short to Ground or Positive Present.

I reset / cleared these faults and they immediately reappeared when I selected the fault report tab.

No faults relating to the door handle antennas though

The corroded grounding points scenario you raised sounds very feasible.

Also when the Durametric was interrogating the Kessy module for the faults, there was an audible noise that was being generated from around the Kessy module location. The noise was someting like rubbing your fingernail tips across your keyboard keys 2 or 3 times.
I repeated the interrogation of the Kessy and sure enough the noise appeared again each time.
I have also heard this noise also when I first drive off in the mornings for about 15 seconds.
Noise was also there when the Kessy was working perfectly though.
Sounds weird huh....I wish I was kidding
What's up with the Kessy doc?

porsche52

This is the fault flow chart for fault code 183, Interior antenna (short to ground/ B+)

This diagnosis/troubleshooting relates to all fault types for
which a 'short circuit to B+' is detected:

Work instruction Display

1 Check wiring harness for short circuit to terminal 30 (constant power 12v)
♦ Switch off ignition
♦ Pull off plug A on control module
♦ Measure voltage between control module plug A, pin 25, pin 26, pin 27, pin 28 and ground.
Voltage is 0 V Display OK =
Step 2
Voltage is greater than 0 V Display Not OK = Repair wiring harness

Step 2 Carry out visual inspection of wiring harness
♦ Switch off ignition
♦ Check wiring harness
from control module plug A, pin 25, pin 26, pin 27, pin 28 to interior antennas for damage, abrasion or crushing, and repair if possible, or replace
Wiring harness OK =
Step 3
Wiring harness Not OK = Repair wiring harness from control module to both interior antennas → End

If nothing turns up from the checks above then it says to replace the Kessy CU.

3 Replace control module → End

porsche52

This diagnosis/troubleshooting relates to all fault types for
which a 'short circuit to B+' is detected: Fault code 181 rear bumper antennas

Work instruction Display
1 Check wiring harness for short circuit to terminal 30
♦ Switch off ignition
♦ Pull off plug A on control module
♦ Measure voltage between control module plug A, pin 46 and ground and pin 47 and ground
Voltage is 0 V = OK→
Step 2
Voltage is greater than 0 V = Repair line → End

2 Carry out visual inspection of wiring harness
♦ Switch off ignition
♦ Check wiring harness from control module plug A, pins 46 and 47 to rear bumber antennas for damage, abrasion or crushing, and repair if possible, or replace
Wiring harness OK =
Step 3
Wiring harness Not OK =Repair wiring harness from control module to both
bumper antennas → End

Once again, if no faults turn up it says to replace the Kessy CU

3 Replace control module → End

bigbuzuki

Well, my antennas have turned up at the service centre.

I will be there first thing in the morning to get them installed.

bigbuzuki

They replaced the interior and rear bumber antennas along with the Kessy control unit, only to have the control unit "blow up" after 5 minutes.

Next they fitted a new "alarm control unit" and another Kessy control unit.

End result is that my keyless entry is working better than ever. Very crisp and sharp response as soon as you touch the door handle.

What do you think P52 ?

porsche52

Very cool! My guess is the Kessy control unit was the problem. I'm a little confused with your post, to me alarm control unit = Kessy/Immobilizer control unit. Any who glad they fixed for ya