How do I find how the Master Break Cylinder and Break Lines connect to the ABS hydraulic ECU unit?

2000 2005 Chevy Impala need break diagram lines running from master cylinder back down to the two bottom or the top run front or what

now the question is
did you get the original master cylinder as a replacement or did you get a new master cylinder for the car that the callipers came off
understanding that there is a direct relationship between master cylinder piston size and calliper piston size, you problem appears to be that there is not enough surface area in the master cylinder to effectively push the calliper pistons out to apply the correct braking pressure
mixing and matching with brakes requires a lot of hydraulic knowledge and pressure differences which include fitting a proportioning valve in the rear brake lines to prevent brake lock up at the rear wheels

Give some more details of the problem.

There is no seperate pump. The following lines will give you more details

Braking force and the tendency of the wheels to lock up are affected by a combination of factors such as the friction coefficient of the road surface, and the difference between the vehicle speed and the road wheel speed. The ABS prevents the road wheels from locking up during heavy braking by controlling the vehicle's brake system hydraulic pressure.
During normal braking, as the rotational speed of the wheel falls, no electric current flows from the ECU to the hydraulic unit. The solenoid valve is not energized. The brake master cylinder hydraulic pressure is applied to the brake unit, and the ABS is not involved. However, even though the ABS is passive during normal braking, its control module is constantly monitoring for rapid deceleration of any of the wheels.
If a wheel-speed sensor signals severe wheel deceleration - which means the wheel is likely to lock up - the ECU sends a current to the hydraulic unit. This energizes the solenoid valve. The action of the valve isolates the brake circuit from the master cylinder. This stops the braking pressure at that wheel from rising, and keeps it constant.
If the sensors signal the wheel is still decelerating too rapidly, the ECU sends a larger current to the hydraulic unit. The armature moves even further and opens the valve. It opens a passage from the brake circuit. Brake fluid is sent from the brake circuit back to the master cylinder. Pressure in the brake caliper circuit is reduced so that the wheel is braked less heavily.
If the wheel sensors indicate that lowering the brake pressure is letting the wheel accelerate again, the ECU stops sending current to the hydraulic unit and de-energizes the solenoid valve. This lets the pressure increase, so that the wheel is again decelerated.
This cycle repeats itself about four to six times per second.
It is normal in an ABS for the valves in the hydraulic control unit to keep changing position as they change the brake pressure that’s being applied. These changes in position may cause rapid pulsations to be felt through the brake pedal.

It doesn't connect to master cylinder. The line should connect to a proportioning valve, then from valve to master cylinder.Star at master cylinder and follow lines to proportioning valve.

It could be the ABS unit it's self that is at fault

Below the Brake Master Cylinder and slightly back towards the Fire Wall. Should have multiple brake lines running into it.
Hint: Most people want to replace these. Alot of times the connections are merely corroded or have build up on the conductors or in the conductor "pits". Clean both and check before going to the expense of replacing. I did and it worked and saved me $$ not having to replace.

your break line is 2 ply, the inner lining is broken and acting as a check valve.

Yes you can disable ABS. First, You said you loose brake pressure. Does your brake system have a vacuum booster and a master cylinder or is the master cylinder abs hydraulic assembly all built together?

Brake Lines and Hoses
Double-walled steel line is used in the hydraulic lines between the brake master cylinder and the front tube connector, and between the brake master cylinder and the flexible brake hose at the rear wheels.
Double-flared brake lines provide good leak-proof connections.
When replacing hydraulic brake lines, hoses, or connectors, tighten all connections securely. After replacement, bleed the brake system; refer to Section 206-00 .
The wet appearance of the outer cover of the rubber brake hose is referred to as "sweating." This is a normal condition for neoprene rayon braid hose and is not a sign of leakage or cause for replacement of the hose.

Hydraulic Brake System Components — Non-ABS


Item Part Number Description 1 2005 Power Brake Booster 2 2455 Brake Pedal 3 2261 Rear Wheel Cylinder 4 2552 Rear Disc Brake Caliper— (Mexico Only) 5 2B120 Disc Brake Caliper—, Front 6 2B091 Brake Pressure Control Valves 7 2140 Brake Master Cylinder