14.8. Check of the vacuum amplifier of brakes
Step 1
| PERFORMANCE ORDER |
| 1. At the switched-off engine, several times press a brake pedal. |
| 2. Launch the engine. |
 |
3. If the pedal of a brake moves down at once after launch of the engine, it demonstrates normal operation of the vacuum amplifier of brakes. |
|
Step 2
| PERFORMANCE ORDER |
| 1. Launch the engine. |
| 2. In 1–2 minutes stop the engine. |
| 3. Press a brake pedal with usual effort. |
 |
4. If the first course of a pedal – the long and second course, is shorter than the first course, it demonstrates normal operation of the vacuum amplifier of brakes. |
| 5. Otherwise check the unilateral vacuum valve or a vacuum hose for absence of damage and check reliability of their fastenings. |
|
Step 3
| PERFORMANCE ORDER |
| 1. Launch the engine. |
| 2. Press a brake pedal with usual effort. |
| 3. Stop the engine. |
| 4. Slowly press a brake pedal, and hold it pressed within 30 seconds. |
 |
5. If height of a pedal does not change, the vacuum amplifier of brakes works normally. |
| 6. Otherwise check the unilateral vacuum valve or a vacuum hose for absence of damage and check reliability of their fastenings. |
|
If malfunction is still not eliminated, execute more detailed survey, using the manometer and the vacuum gage.
