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Home >> Jaguar >> 2019 >> XJR575 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Brake System - General Information -- XJ/X351 >> Brake System - General Information (G1269564) >> Diagnosis And Testing >> Brake System (G2871762) >> Pinpoint Tests >> Pinpoint Test I: The Pedal Feels Spongy

Pinpoint Test I: The Pedal Feels Spongy

  1. I1: CHECK FOR SPONGY PEDAL (ENGINE OFF) 
    1. Check for a firm brake pedal

      Is the brake pedal effort and brake pedal travel normal?

      Yes 

      No action is required, vehicle is OK

      No 

      GO to  I2.

  2. I2: CHECK BRAKE PEDAL RESERVE (ENGINE OFF) 
    1. Pump the brake pedal 10 times and hold on the final application

      Does the brake pedal feel firm on final application?

      Yes 

      GO to  I3.

      No 

      Bleed the brake system

  3. I3: CHECK BRAKE PEDAL RESERVE (ENGINE ON) 
    1. With engine running at idle speed
    2. Apply the brake pedal lightly three or four times
    3. Wait 15 seconds for the vacuum to recover
    4. Push down on the brake pedal until it stops moving downward or an increased resistance to the brake pedal travel occurs
    5. Hold the brake pedal in the applied position while increasing the engine speed to 2000 revs/min
    6. Release the accelerator pedal

      Does the brake pedal move downward as the engine speed returns to idle?

      Yes 

      GO to  I4.

      No 

      Check the vacuum to brake booster

  4. I4: CHECK BRAKE FLUID LEVEL 
    1. Check the brake master cylinder reservoir fluid level

      Is the fluid level OK?

      Yes 

      Bleed the brake system. Re-test the system for normal operation

      No 

      Check for leaking brake system and rectify as required. Add fluid and bleed the brake system. Re-test the system for normal operation

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