[Doug Pizzy]

I have a 2015 PMC with about 43K on it that I bought in July with 37K. Yesterday I noticed the parking brake light on the dash would stay on after I disengaged the brake. It would go off after a few minutes and did it about half the times I used the parking brake. Same thing happened today except one of the times a message came on the dash that said "Service Brake Pads" or "Brake Pad Service Needed". The message disappeared within seconds and never came on again.
I'm not surprised that I may need new brakes as I have noticed a bit of front end shaking when I brake at high speeds. I'm wondering if the pkg brake light staying on periodically is an early warning or is related to the service msg about the pads.
How long do brake usually last on a PMC? I doubt that the previous owner had replaced them in the first 37K miles.

 

[Crabapple]

The parking brake works off the rear brakes. Which on the PMC are drum brakes, not disk brakes like the fronts . I suspect that the light is just a sticky solenoid switch or possibly the actuation cable needs lubrication somewhere. This is common issue on vehicles where parking brake is seldom used. The beauty of drum brakes is they rarely need servicing. Your front disk brakes do need some attention if you are getting shaking up front under braking. Rotor and pad life can vary considerably based on usage and environmental conditions, difficult to generalize. From your description could be a warped rotor

 

[Doug Pizzy]

I actually use my parking brake all the time, especially in my driveway because it's very steep.
The parking brake light used to come on in my Tacoma if the brake fluid wasn't filled all the way up past the fill line. As soon as it got to the fill line it would come on and off going around corners. I thought that might have been the problem with the PMC.

 

[Crabapple]

Parking brakes are usually cable actuated, not hydraulic

 

[B1GBLEU]

Parking brakes are usually cable actuated, not hydraulic

which could be a stretched out cable

 

[bobcomptonphoto]

Sensor light

I had the same issue. Turns out that the working brake pads ALSO have a sensor, and the parking light is the first line of telling you that they are worn. I took mine in and had to get a brake job.