Brake Booster Inspection

Special Tools Required Vacuum gauge 07404-5790301 Pressure gauges 07406-5790201
Attachment
07410-5790101
Tube joint adapter
07410-5790501
Pressure gauge joint pipes, 10 x 1.0 mm
07510-6340101
Oil pressure attachment
070AJ-S3V0100
Oil pressure hose
07FPJ-7520100
Pressure gauges set
07YAJ-0010410
Leak Test

1. Install the vacuum gauge (A) between the brake booster and check valve.

1. Start the engine, adjust the engine speed with the accelerator pedal so that the vacuum gauge readings show 40.0−66.7 kPa (300−500 mmHg, 11.8−19.7 in.Hg), then stop the engine.

1. Read the vacuum gauge.
   If the vacuum reading decreases 2.7 kPa (20 mmHg, 0.8 in.Hg) or more after 30 seconds, check following parts for leaks.
   - Check valve
   - Vacuum hose, pipe
   - Seals
   - Brake booster
   - Master cylinder
   NOTE: Do not try to disassemble the brake booster. Replace the brake booster as an assembly with a new one.

Function Test

1. Install the vacuum gauge the same as the leak test.

1. Connect the oil pressure gauges (A) to the master cylinder using the attachments (special tools) as shown.

1. For ABS type, bleed air through the valves (B).

1. Start the engine and let it idle.

VSA type
ABS type

1. Have an assistant depress the brake pedal with a 98 N (10 kgf, 22 lbf) and 294 N (30 kgf, 66 lbf) of pressure measuring with a commercially available pressure gauge (A).

1. The following pressures should be observed at the pressure gauges in each vacuum.

   Vacuum booster vacuum kPa (mmHg, in.Hg) | Brake pedal pressure N (kgf, lbf) | Master cylinder oil pressure kPa (kgf/cm 2 , psi)
   0 (0, 0) | 98 (10, 22) | 0 (0, 0)
   294 (30, 66) | 545 (5.6, 79)
   66.7 (500, 19.7) | 98 (10, 22) | 5,015 (51.1, 727)
   294 (30, 66) | 9,570 (97.6, 1,388)

1. Inspect the master cylinder for leaks if the readings do not fall within the limits shown above.

Booster Check Valve Test

1. Disconnect the brake booster vacuum hose (check valve built in) (A) at the booster side.

1. Start the engine, and let it idle. There should be vacuum available. If no vacuum is available, the check valve is not working properly. Replace the brake booster vacuum hose and check valve, and retest.