Audi Workshop Service and Repair Manuals

Checking vacuum pump -V192- Description and function The electrical vacuum pump is switched on by the engine control unit, depending on intake manifold pressure. The vacuum pump is capable of self-diagnosis. Recognised faults are stored in the engine control unit.   Note The engine must not be running when you check the function of the electric vacuum pump via self-diagnosis. Special tools and workshop equipment required t  Vehicle diagnosis, testing and information system -VAS 5051B- or -VAS 5052-

Procedure –  Switch off ignition. –  Press brake pedal repeatedly („pump the brake servo dry“) until there is no more servo assistance and the brake pedal is heavy. –  With ignition switched off, connect vehicle diagnostic, testing and information system -VAS 5051B- or -VAS 5052- to 16-pin diagnostic connector in vehicle.

–  Switch on vehicle diagnosis, testing and information system. The tester may need up to 3 minutes before it is ready for operation. –  Switch on ignition. –  Select mode: Press the button on the display for „Vehicle self-diagnosis“. –  Select vehicle system: Press the button for „01 - Engine electronics“. The control unit identification and coding will appear at the top right of the display. –  Select diagnosis function (all diagnosis functions are available at this stage). –  Select „006 - Basic setting“ on the display. –  Press buttons 0, 0 and 8. –  Confirm entry with Q key. The following information will appear at the bottom of the display:

Basic setting
	Not operated
	Pump off
	xxx mbar
	Test off

–  To start the test, select „activate“ on the display. The following information will appear at the bottom of the display:

Basic setting
	Not operated
	Pump on
	xxx mbar
	Test on

Do not press the brake pedal again once the test has been activated. The vacuum pump for brakes -V192- supplies vacuum to the brake servo. The diagnosis of the brake servo system runs in the control unit at the same time. The system passes the test if the pressure in the brake servo reaches the shut-off threshold within the time limit set by the diagnostic function. The following information will appear at the bottom of the display:

Basic setting
		Not operated
		Pump off
		xxx mbar
		Syst. OK

–  You can cancel or exit from this mode by pressing the Go to button. The system fails the test if the pressure in the brake servo does not reach the shut-off threshold within the time limit set by the diagnostic function. The following information will appear at the bottom of the display:

Basic setting
	Not operated
	Pump off
	xxx mbar
	Syst.n.OK

–  Follow „Guided Fault Finding“ procedure using vehicle diagnostic, testing and information system -VAS 5051-. To repeat the test, switch the ignition off and then on again.