New brakes failed, broken speed sensor to tire

Hi and thanks for using 2CarPros.com.

The speed sensor will not prevent the brakes from working. It will, however, prevent the anti lock system from working. If the brake pedal goes to the floor, check for leaking, rusted steel brake lines. Also, make sure the rubber brakes hoses to the calipers are not leaking. If no leaks are evident and the brake fluid remains full in the master cylinder, suspect a bad master cylinder.

Take a look through this link and see if it is what you are experiencing.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

If you determine the master cylinder is bad, here are the directions for replacement. The attached pictures correlate with these directions.

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REMOVAL
1. Disconnect level warning switch connector.
2. Take out fluid with syringe.

NOTICE: Do not let brake fluid remain on a painted surface. Wash it off immediately.

3. Disconnect brake lines.
Using Special Service Tool (SST) 09023-00100 or equivalent, disconnect the 6 (w/o ABS) or 2 (w/ ABS) brake lines.
Torque: 15 Nm (11 ft. lbs.)
4. Remove master cylinder.
Remove the 2 nuts, 4-way (w/o ABS), check valve bracket, bracket and pull out the master cylinder and gasket.
Torque: 13 Nm (9 ft. lbs.)

INSTALLATION
Installation is in the reverse order of removal.
1. Before installation, adjust length of brake booster push rod.
a. Install a new gasket on the master cylinder.
b. Set the (SST) 09737-00010 on the gasket, and lower the pin until its tip slightly touches the piston.
c. Turn the (SST) upside down, and set it on the booster.
d. Measure the clearance between the booster push rod and pin head (SST).
Clearance: 0 mm (0 inch)
e. Adjust the booster push rod length until the push rod lightly touches the pin head.
2. After installation, fill brake reservoir with brake fluid, bleed brake system, check for leaks, check and adjust brake pedal.

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Let me know if this helps.

Take care,
Joe

A broken speed sensor would not cause your brakes to fail. It might cause the ABS light and brake light to come on, and your car would be on 1980's brakes (No ABS), but the car would stop pretty normally when you push the brakes under normal conditions. Before I say any more, let me get some clarification first. Exactly what do you mean when you say that the brakes fail? Is the pedal going to the floor and the car is not stopping? Or is something else going on? Please be as detailed as possible. Thanks!