Hey, I have an 02 xlt. I’ll post more details in a comment, but I just replaced my brakes, calipers, and rotors after losing my brakes on the highway. One second they worked fine, the next my pedal goes straight to the floor w no resistance. I replaced my brake lines last fall, but now that I’ve gotten everything replaced, the pedal is still dropping straight down w no resistance. I replaced the booster and master cylinder. When the truck is off, the pedal feels normal, but as soon as I turn it on, it’s gone again. I’ve bled the brakes, and the cylinder. I don’t know what else to do.

 

2002: 4WD 3.0L MFI FFV OHV 6cyl
Rotors and calipers in the front, with drums in the rear. No visible leaks.

 

Why did you lose your brakes?
Did a brake line come off or break?

Master has two brake reservoir/pistons and two OUT lines
Front line goes to rear brakes
Back line goes to front brakes

Both lines go to the 4 wheel ABS units, but are kept separate inside the unit so you can't "lose all brakes"

If a brake line should break then you would only lose the 2 front brakes or the 2 rear brakes, pedal would go the the floor but if you pumped it either front or rear brakes would start to work to slow you down and stop you, at least until Master ran out of fluid

The 4WABS units are hard to bleed without the Ford electronic tool that opens and closes the valves, si if you think you got air in that unit then you will need to bleed it
Google: ford ranger 4wabs bleeding


Engine off
Take the cap off the Master
Open passenger side rear brake bleeder with a pan down to catch the fluid
Let fluid run out, called gravity bleeding, for 1 minute or so, then close bleeder
Then do the same on drivers side rear wheel

Then do passenger front and drivers front
watch for bubbles

 

The line popped off the caliper. I had to use the parking brake to stop myself since the brake wasn’t working. I’ve replaced everything, I gravity bled them this morning to no avail. I’ll try looking at the 4wabs stuff.

 

Update: I bought the $400 OBD2 reader that bleeds the abs system. I have no air coming out of the lines anymore, yet my pedal still goes straight to the floor. Any advice? Should I just take it to a shop and have them look at it? Is it worth the money?

 

When you replaced the master cylinder did you bench bleed it before you installed it? It can be difficult to get the air out with it installed in the truck. I have not installed a Ranger master, but I have installed a couple that came with two short plastic lines that allowed them to be directed into the reservoir. It took a fair amount of work to get all the air out, using a screw driver to pump the piston.

 

yeah, I pumped it for about 15 mins straight. Took the tubes and had them spit it back into the reservoir. With the truck off the brakes feel perfectly fine. But as soon as I start it they go back to no resistance. Then I have to turn the truck off and then pump the brakes again (roughly 40 times) to get the pressure back. Pumping while running does nothing.

 

It reads like a bad Master, new or not

If you have a helper have them get in the vehicle engine off
Have them press down on brake pedal
Then you open a rear bleeder and fluid should of course squirt out until pedal goes to the floor, then close bleeder
Now do the same but on either front wheel
Should be the same squirting strength
If front or rear is different then bad Master

Master has 1 reservoir but its shared by the 2 pressure chambers, one for front and one for the rear brake lines
When you press Masters shaft forward each pressure chamber is then cut off from the reservoir so this forward motion now forces fluid out of the two pressure chambers and into their respective brake lines
Power booster is set up for the resistance of BOTH pressure chambers
If one of the pressure chambers has a bad seal then fluid can flow up into reservoir, so no resistance and pedal goes to the floor same as if a brake line was broken on that front or rear system