ATS status; Failed parked Regen/ Park Brake <check>

So last week I tried running a parked Regen but it failed. When I checked the ATS status, the Park Brake and Temporary lockout showed :check: I will add that the parking brake light has never worked since I have owned the truck. I've searched all over and cant find any info on adjusting the brake pedal or where the park brake switch is located. Now to add to that.. I stopped at the dealer on my way home and they cleared a bunch of codes, but Temporary lockout is still showing :check: and my parking brake light worked for a few minutes, then stopped working again..
The reason for all this is my DPF light started flashing on my trip (stage2) and I was just trying to make it home before having issues. I'm going to remove the filter to see if they can cook it clean. Now would that cause an EGR Temp to high (MID 128 PID 412 FMI 0) or is my EGR valve on its way out?

Thanks in advance for any help!

Truck info is: 2008 VNL780 D16/iShift with 874,000 miles

 

Thanks Benek. What is strange, I tried to run a parked Regen while at the dealer (when the light was working) and it still failed. I have a Park Brake switch on order and still plan to have the DPF cooked...

 

Prior to making it to the dealer when the DPF light was flashing.... it was requesting a parked regen. Dealer cleared all codes, so does that mean I would have to go back to the dealer?

 

Ok, so I found the Park Brake switch... Nicely packed in as well... I made a jumper wire and tested to see if it would enable the dash light. Which it did. Now, how do you remove it? It just spins on itself which I assume it is not supposed to do.
On another note, I removed the DPF to get it cooked. I found an exhaust leak at the top cover and it doesnt look like its been leaking for that long. It also doesnt look anywhere near as bad as I expected.

Now what would cause high temps on the EGR? Just failing and needing to be replaced?

Thanks in advance