ABS and Parking Brake light on

C0265 is an internal abs unit problem. so the abs needs to be replaced. cheapest way for you to do this is to remove abs and send it in for a rebuild, check online for prices or check with auto parts as the truck will need to be laid up for a while. This video will how you how

https://youtu.be/lUotkKXG9dY

then you'll need a pro to bleed the system due to he will need to use a scanner to hold valves open in abs to bleed it properly.