Attention: when checking the non-return valve, it must be connected to the vacuum hose.
1. Remove the vacuum hose.
Note: when removing the vacuum hose, do not disconnect the non-return valve from it.
2. Check the operation of the non-return valve using a manual vacuum pump according to the table below.
Table. Checking the vacuum booster check valve.
| Vacuum pump connection | Criteria for admission / refusal |
| From the side of the brake booster (1) | Vacuum is created and maintained |
| From the intake manifold (2) | Vacuum is not created |
Attention: if the non-return valve is defective, it must be replaced complete with a vacuum hose.
Checking the operation of the vacuum brake booster using pressure gauges
1. Connect pressure gauges and vacuum gauge as shown.
2. Test the amplifier with no load.
Start the engine. Stop the engine when the vacuum reaches 67 kPa. After stopping the engine for 15 seconds, the vacuum does not drop.
3. Perform a load test on the amplifier.
Start the engine and press the brake pedal with a force of 200 N. Stop the engine when the vacuum is 67 kPa. After stopping the engine, the vacuum will decrease to approximately 3.3 kPa.
4. Carry out a test with the vacuum booster not running.
Stop the engine. Make sure the vacuum is 0 kPa. Make sure that the brake fluid pressure is within the limits for 100 N and 300 N brake pedal force.
Brake fluid pressure when the vacuum brake booster is not working (sedan).
| Effort on the brake pedal, N | Brake fluid pressure, kPa |
| 100 | 0 |
| 300 | 1824 |
Brake fluid pressure when the vacuum brake booster is not working (station wagon).
| Effort on the brake pedal, N | Brake fluid pressure, kPa |
| 100 | 0 |
| 300 | 1582 |
5. Perform a performance test on the amplifier.
Start the engine. When the vacuum reaches 67 kPa, check that the brake fluid pressure corresponds to the maximum permissible values at the effort on the brake pedals of 100 N and 300 N.
Brake fluid pressure with vacuum brake booster running (sedan).
| Effort on the brake pedal, N | Brake fluid pressure, kPa |
| 100 | 4432 - 4938 |
| 300 | 10421 - 10927 |
Brake fluid pressure with vacuum brake booster running (station wagon).
| Effort on the brake pedal, N | Brake fluid pressure, kPa |
| 100 | 4399 -4839 |
| 300 | 12162 - 12602 |
Note: if the results of one of the checks carried out were unsatisfactory, then you should look for a malfunction in the vacuum hose, check valve and vacuum brake booster.