Tests Note

Operation of the pump is regulated by means of the ignition key for testing purposes.

Position 0 = Pump off

Position 1 = Pump on until switched off by the pressure warning switch.

2004-47

- In ignition key position 0, plug the electrical plug onto the pump. Locate the pressure gauge in a position where it can be seen.

- For the tests, it is expedient to observe the a. Pressure accumulator - Gas filling pressure b. Switching points for the brake pressure c. Cut-in and cut-out points of the pump d. Leak test

Turn the ignition key to position 1 (pump a. Gas filling pressure of the pressure

Turn the ignition key to position 0 at approx. 100 bar.

Operate the brake pedal several times and observe the pressure gauge. When the indicator falls rapidly towards zero, the filling pressure of the pressure reservoir has been reached. For required values, see page 47-24.

Note

Sensitively operate the brake pedal shortly before the gas filling pressure is reached.

b. Checking the switching points for the brake pressure warning lamp.

Pressure build-up:

Start the engine and observe the warning lamp. Immediately turn the ignition key to 0 position at the instant when the warning lamp goes out. Read off the pressure on the pressure gauge.

Pressure reduction:

Produce a system pressure of approx. 140 bar. Disconnect the plug at the pressure pump.

Start the engine

Operate the brake pedal sensitively several times until the warning lamp lights up. Read off the pressure on the pressure gauge. Refer to Page 47 - 24 for nominal values.

Cut-out pressure: Turn the ignition key to position 1. The electrical plug must be plugged onto the pressure pump for this. Read off the pressure on the pressure gauge immediately after independent pump cut-out.

Cut-in pressure: Turn ignition key to position 1. Wait until the pump sw/itches off independently if appropriate. Press the brake pedal as often as required until the pump starts up. Read off the pressure on the pressure gauge at this instant. Refer to Page 47-24 for nominal values.

d. Checking the pressure loss of the booster circuit.

Turn the ignition key to position 1. Wait until the pump cuts out independently. Press the brake pedal as often as required until the pump starts up again. After independent cutout of the pump, turn the ignition key to posi tion 0 and disconnect the electrical plug at the pump. No longer operate the brake pedal. Measure the pressure drop over the course of time. Refer to Page 47 - 24 for permitted values.

Depressurize the booster circuit before remov-

c. Checking the switching points of the pressure pump

47 01 01 Pressure test on brake booster circuit

Printed in Germany -13, 1985

Brakes, Hydraulics, Regulator. Booster 911 Carrera (993)

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