I am new to DF, So here we go! I have a 1999 Caravan with a 3.3 I use for a winter rat. I needed to replace the BrakeLines from the Master Cylinder to the Hydraulic Control Unit,This was no promble at all.
After doing so I went to bleed the brake system,Starting with the passenger rear first. We were able to pump new fluid threw it as you would any other car. Now going to the Driverside rear wheel the pedal started showing signs of getting extremly hard to pump and after taking the bleeder screw out all the way, NO fluid would come out. Not sure what is going on, I moved to the driverside frontwheel, no fluid coming out and the brake pedal is rock hard and no brakes! Now going to the book,It tells me a DRBII Scan tool is needed to now bleed the lines. What dose this tool do?The few repair shops I talked to have no idea what Iam taking about,never heard of such a thing and don't have a Tech that knows what to do. Any ideas? or how to get around this. I can't drive the van, NO Brakes

 

I don't think the problem will be ur HCU.
You probably Kink some of the brake lines u installed. Disconnect the brake lines u did on the HCU, pump the pedal or just fill up the fluid bottle, see if brake fluid squirts out. You want to figure out if the problem is before or after the HCU first.

 

Welcome to DF
Try this first and yes you need a scan tool to bleed the ABS.
PROPORTIONING VALVE
A vehicle equipped with ABS uses a fixed proportioning valve.

On a vehicle equipped with ABS, premature or excessive rear wheel ABS cycling may be an indication that the brake fluid pressure to the rear brakes is above the desired output.

Prior to testing a proportioning valve for function, check that all tire pressures are correct. Also, ensure the front and rear brake linings are in satisfactory condition. It is also necessary to verify that the brakes shoe assemblies on a vehicle being tested, are either original equipment manufacturers (OEM), or original replacement brake shoe assemblies meeting the OEM lining material specification. The vehicles brake system is not balanced for after market brake shoe assembly lining material.

If brake shoe assembly lining material is of satisfactory condition, and of the correct material specification, check for proper proportioning valve function using the following procedure.

Road test vehicle to be sure the vehicle is truly exhibiting a condition of excessive rear wheel ABS cycling. Since ABS cycles both rear brakes together both proportioning valves of the assembly Rear Brake Proportioning Valve And Brake Tube Locations must be tested. Use the following procedure to test the proportioning valve
Remove one of the chassis brake lines Rear Brake Proportioning Valve And Brake Tube Locations coming from the ABS modulator, at
the proportioning valve assembly. Remove the hydraulic brake line going to one of the rear wheels of the vehicle from the proportioning valve Rear Brake Proportioning Valve And Brake Tube Locations
Remove the 2 bolts Rear Brake Proportioning Valve And Brake Tube Locations attaching the proportioning valve to the frame rail
CAUTION: When lowering the proportioning valve, care must be taken not to kink any of the chassis brake lines.

Carefully lower the proportioning valve for clearance to install the proportioning valve test fittings.
Install the required fitting from Pressure Test Fittings, Special Tool 6833 Proportioning Valve Test Fitting Installation into the inlet port of the proportioning valve assembly, from which the chassis brake line was removed. Install the removed chassis brake line into the Pressure Test Fitting Proportioning Valve Test Fitting Installation Install the required fitting from Pressure Test Fittings, Special Tool 6833 into the required outlet port of the proportioning valve. Install the required fitting from Pressure Test Fittings, Special Tool 6833 into the required outlet port of the proportioning valve Proportioning Valve Test Fitting Installation Then install the removed chassis brake line into the Pressure Test Fitting Proportioning Valve Test Fitting Installation
Install a pressure gauge from Gauge Set, Special Tool C-4007-A into each pressure test fitting Pressure Gauges Installed On Pressure Test Fittings Bleed air out of hose from pressure test fittings to pressure gauges, at the pressure gauges Pressure Gauges Installed On Pressure Test Fittings Then bleed air out of the brake line being tested, at that rear wheel cylinder
With the aid of a helper, apply pressure to the brake pedal until a pressure of 6895 kPa (1000 psi) is obtained on the proportioning valve inlet gauge. Then based on the type of brake system the vehicle is equipped with and the pressure specification shown on the following table, compare the pressure reading on the outlet gauge to the specification. If outlet pressure at the proportioning valve is not within specification when required inlet pressure is obtained, replace the proportioning valve.
Repeat steps 2 through 7 for the other proportioning valve of the assembly
CAUTION: When mounting the original or a replacement proportion valve on the frame rail of the vehicle install the mounting bolts in only the two forward holes of the mounting bracket Rear Brake Proportioning Valve And Brake Tube Locations Proportioning valve split point pressure conversion is 1 bar is equal to 14.5 psi.

WHEEL BASE DRIVE TRAIN SALES CODE BRAKE SYSTEM SPLIT POINT SLOPE INLET PRESSURE PSI OUTLET PRESSURE PSI
SWB FWD BRA-BGF 14" DISC/DRUM W/O ANTILOCK VAR. .30 1000 PSI 250-350 PSI
SWB FWD BRA+BGFBRB+BGFBRV+BGF 14",15",15"HD DISC/DRUM WITH ANTILOCK 25 BAR .59 1000 PSI 660-780PSI
LWB FWD BRA-BGF 14" DISC/DRUM W/O ANTILOCK VAR. .30 1000 PSI 250-350 PSI
LWB FWD BRA+BGFBRB+BGFBRV+BGF 14",15",15"HD DISC/DRUM WITH ANTILOCK 25 BAR .59 1000 PSI 660-780 PSI
LWB AWD BRE+BGF 15" DISC/DISC WITH ANTILOCK 41 BAR .36 1000 PSI 690-800 PSI