Ford Thunderbird/Cougar 1983-1997 Repair Guide

Bleeding The ABS System


The brake system must be bled any time air is permitted to enter the system through loosened or disconnected lines or hoses, or anytime the modulator is removed. Excessive air within the system will cause a soft or spongy feel in the brake pedal.

When bleeding any part of the system, the reservoir must remain as close to full as possible at all times. Check the level frequently and top off fluid as needed.

When any part of the hydraulic system has been disconnected for service, air may enter the system and cause spongy pedal action. Bleed the system after it has been opened to be sure that all air is expelled.

The anti-lock brake system must be bled in 2 steps; both the master cylinder and hydraulic control unit reservoir must be bled using Rotunda Anti-Lock Brake Breakout Box/Bleeding Adapter tool No. T90P-50-ALA or equivalent. If this procedure is not followed, air will be trapped in the hydraulic control unit, and will eventually lead to a spongy brake pedal.

  1. Disconnect the 55-pin plug from the electronic control unit/ABS control module, then install Anti-Lock Brake Breakout Box/Bleeding Adapter tool No. T90P-50-ALA or equivalent to the wire harness 55-pin plug.
    1. Place the Bleed/Harness switch in the BLEED position.
    3. Turn the ignition to the ON position. At this point the red OFF light should come ON .
    5. Push the motor button on the adapter down to start the pump motor. The red OFF light will turn OFF , and the green ON light will turn ON . The pump motor will run for 60 seconds after the motor button is pushed. If the pump motor is to be turned off for any reason before the 60 seconds have elapsed, push the abort button to turn the pump motor off.
    7. After 20 seconds of pump motor operation, push and hold the valve button down. Hold the valve button down for 20 seconds, then release it.
    9. The pump motor will continue to run for an additional 20 seconds after the valve button is released.

  3. The brake lines can now be bled in the normal fashion. Bleed the brake system by removing the rubber dust cap from the caliper fitting at the right rear of the vehicle. Place a suitable box wrench on the bleeder fitting and attach a rubber drain tube to the fitting. The end of the tube should fit snugly around the bleeder fitting. Submerge the other end of the tube in a container partially filled with clean brake fluid and loosen the fitting 3 / 4 turn.

Brake fluid absorbs moisture from the air. Don't leave the master cylinder or the fluid container uncovered any longer than necessary. Be careful handling the fluid-it will damage the vehicle's paint.

Check the level of the fluid often when bleeding, and refill the reservoirs as necessary. Don't let them run dry, or you will have to repeat the process.

  1. Have an assistant push the brake pedal down slowly through its full travel. Close the bleeder fitting and allow the pedal to slowly return to its full release position. Wait 5 seconds and repeat the procedure until no bubbles appear at the submerged end of the bleeder tube. Secure the bleeder fitting and remove the bleeder tube. Install the rubber dust cap on the bleeder fitting.
  3. Repeat the bleeding procedure at the left front, left rear and right front (in that order). Refill the master cylinder reservoir after each caliper has been bled, and install the master cylinder cap and gasket. When brake bleeding is completed, the fluid level should be filled to the maximum level indicated on the reservoir.
  5. Always make sure the disc brake pistons are returned to their normal positions by depressing the brake pedal several times until normal pedal travel is established. If the pedal feels spongy, repeat the bleeding procedure.

After finishing, there should be no feeling of sponginess in the brake pedal. If there is, either there is still air in the line, in which case the process must be repeated, or there is a leak somewhere, which, of course, must be corrected before the vehicle is moved. After all repairs and service work is finished, road test the vehicle to verify proper brake system operation.