Check warning trigger points - AR42.50-P-0001-08MB

The ignition must be switched off.

1. Release pressure from booster circuit (depress brake pedal approximately 30 times).
2. Switch on the ignition and wait until the motor-and-pump assembly is deactivated.
3. Remove fuse (f8, 40 ampere) for relay K37/1.
   Fig 1: Identifying Fuse

   
4. Quickly depress the brake pedal a number of times in succession to depressurize the booster circuit.

   At 101 -107 bar the warning "BRAKE SYSTEM - WAIT-PRESSURIZATION" should appear in the instrument cluster's display.

   The motor-and-pump assembly starts to run.

   At approximately 135 bar the warning display should go out again.

   Conditions met: System OK

   Fails to comply with conditions: ESP control unit or vehicle electrical system defective.

5. Install fuse (f8, 40 amperes) for relay K37/1.
6. Switch off ignition.
   Fig 2: Checking Warning Trigger Points