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Need help diagnose non-opening trunk

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I have a 2004 Cayenne S.

My trunk won't open anymore. It's the regular one, not the power tailgate.

The window on the tailgate still opens fine (and I go through there to access the unlock mechanism by hand for now, but it's tiring).

When I press the electric button, I don't hear the actuator, the door stays locked.

I've replaced the actuator, it was cheap enough ($20) but it still won't work.

I have access to a Piwis, but I would need directions on where to look to diagnose if the ECU (Kessy ?) gets the information when the unlocking button is pressed.

When talking to the Kessy, the communication gets lost frequently. Could it be a Kessy going bad ?


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Since you have access to a diagnostic tool you can access both kessy and the module labeled "Rear / Doors" this is the rear body module that controls the locks on the rear hatch. If you do not have any relevant fault codes on either of these you are going to have to do some more specific troubleshooting. The communications with kessy being lost may be part of the problem or it may be that the module is going to sleep on you. You might try accessing it with the engine running to see if you can stay connected. If you do not have codes that are helpful you might check the handle contact pad. If this pad is not working or has a loose connector it could be the problem.

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