KW 2006 W900 Air Brake issues

Hi, I have a KW 2006 W900 cat C15. I fixed an air leak. I started the truck up to let the pressure build up. The primary gauge went to 130 quickly, the secondary gradually got up to 130. So I shut the truck off, I pushed the valves in, turned the key on, and I started pumping the brakes to do the low air pressure test. The light came on about 60psi and the buzzer never sounded. The air went all the way down to about 5 pounds before for the brake valves pop out.

I have another question. Can the parking brake be bad? Thanks

Does anyone know what the problem would be? I appreciate any help.

Thank you.

 

I'll look into that. Thank you for the reply, I appreciate it.

 

Thank you.