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Electric Vacuum Pump: Testing

WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2005 Audi allroad, 2004 Audi allroad, 2004 Audi A6, 2003 Audi allroad, and 2003 Audi S6. However, it is still accessible from the selected car via links, so may be relevant.
  1. Electric vacuum pump is tested using VAS 5051 or VAG 1551 scan tool in diagnostic function 04 - BASIC SETTING mode. Before beginning procedure ensure that battery voltage is 11 volts or more, engine and transmission grounds are okay, engine is not running and transmission is in Neutral or Park.
  2. Turn ignition off. Connect scan tool to Data Link Connector (DLC). DLC is located under dash to left of steering wheel. See Figure. Turn ignition on. Following scan tool instructions, navigate to BASIC SETTINGS mode.
  3. On scan tool, press keys "0", "0" and "8" to select "PERFORM SHORT TRIP UP 28" function. Press "Q" key to confirm entry. Press "4" key. Firmly apply brake pedal several times to vent power booster.
  4. When power booster is vented electric vacuum pump should begin to run. Once test has begun DO NOT press brake pedal until testing is complete. Diagnosis of electric vacuum pump is run in parallel in the control module. System passes test if power booster reaches shut-off threshold within specified time (about 20 seconds).
  5. If electric vacuum pump does not run during test, check circuits between vacuum pump and ABS control module. See ANTI-LOCK BRAKE SYSTEM wiring diagram in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If no problem with wiring is found, replace vacuum pump. See ELECTRIC VACUUM PUMP  under REMOVAL & INSTALLATION. If vacuum pump continues to run on, go to next step.
  6. Check for leaks in power booster, vacuum line or vacuum pressure sensor. If problem is found, repair as necessary. After repair, repeat steps  1- 4 .
  7. To verify repairs, on scan tool press "0" and "3" to select "FINAL CONTROL DIAGNOSIS" function. Press "Q" key to confirm entry. Press arrow key until, FINAL CONTROL DIAGNOSIS is displayed. Vacuum pump should run for about 10 seconds.
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