Parking brake not engaging

When this does not work, is there any indicator that it is not working? Meaning is there a message that says there is an issue or the light not come on? Or does everything operate normally but the brake just doesn't engage? In other words, how do you know it is not working?

Here is the process from the manual on how this works and how to do the initialization process. Let's try that and see if it makes an improvement. Basically just press the parking brake button 4 times with the ignition in the on position but the engine off.

Let me know what about this info and we can go from there. Thanks

When the parking brake does not work, the PDC malfunction light comes up and when on a slope the car rolls forward (slightly) when ignition is off. But when the parking brake engages, the car holds like a rock on the slope and no parking brake malfunction indicator. Also when the parking brake is turned off, I can hear the actuator release the brakes. I had opened up the parking brake unit in the car trunk and replaced the plastic actuator with metal one. Also applied some lube.

Okay. If that message comes up then we should have some codes. This is most likely a sensor issue but we need to find out what code is there and then we can determine next steps.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Just make sure the scan tool can communicate with the PDC (most can) and you will be able to pull the codes.

The error code says "00507C, Parking gear Incorrectly Engaged". What baffles me is that it does work sometimes, but not always.

This could be a couple things but I would start with checking the fluid condition and level. I attached the process below on how to check the fluid level but if this park lock is not engaging then it may be this simple which would explain why it works at times.