Brake Bleed

97 4X4 5.O
I was reading some instr. on bleeding my brakes and
I have a couple ?'s. It says to hold open "metering pin"
I am looking at a diagram of the combination valve and
I'm wondering where it is exactly. Also, says to bleed
"isolation/dump valve" on trucks with rear ABS.
Is this on the caliper?
Any help appreciated. I would like to do this tommorrow.
My brakes squeak loud when not pressed and the pedal
is way soft after rotor & wheel cylinder replace. Pads OK.
I am going to replace brake lines, bleed, lube caliper sliders,
use "brake quiet" on back of pads and clean real good.
I don't know what else to do. They are real loud.
Thanks alot

Iam not sure if you have RWAl or 4wABS> The bleeding of the isolation valve is to make sure the aair gets out of the system . The valve is located right on the ABS System and should have a bleeder valve on it. When doing the front Calipers when you start to compress the piston in the calipers crack open the bleeder valve while you are compressing the piston and close it when it is bottomed out. It is to keep dirty brake fluid from pushing back into the ABS pump. Not so much with rear ABS as with 4 Wheel ABS. If you are going to replace the rotors go ahead and replace the pads dont want old pads with new rotors.

Thanks for the reply. I cleaned & lubed the calipers but it seems
the prob. is the edges of the pads on both sides is scraping
the hub part of the rotor since I had the rotors replaced.
The pads had plenty left on them so I didn't replace but
when I got a closer look at them I see they are in bad shape.
The backs are corroded and the edges are all chipped and
the channels in the center of the pads are filled in and fused.
I am going to replace them but I'm not sure that will help. I
thought the clearance looked good when i put the calipers
back on but as soon as I applied the brakes the edges of the
pads snugged up to the rotors again. I think I will let a shop bleed
the whole system because the fluid is real dark and I had a prob.
with one of the bleeders. Someone had already rounded it off.
After I replace the pads I will probably take it back to the shop
that replaced the rotors if still a prob. The passenger rotor is
getting a nice groove already where it's scraping.
Thanks Again

By the way, I just have the rear ABS.
I decided I will take it back tonight to the place
that replaced the rotors before I change the
pads and have them look at the scraping issue.
It occurred to me that the rubbing is what may
have beat up & overheated the pads.