Venting DSC5.7 with the DIS tester

Primary circuit: In the DSC hydraulic control unit, air bubbles can adhere to the edges and valves, and these cannot be removed by rinsing with the brake fluid replacement device. The vibrations that occur during venting with the DIS tester loosen the air bubbles.

Secondary circuit: In the normal case (DSC does not intervene), the secondary circuit is closed, so that air it contains cannot escape on rinsing with the brake fluid replacement device. On venting with the DIS tester, the return pump, the exhaust and high-pressure switching valves are activated during rinsing so that also the secondary circuit is vented.

Precharge pump: After replacement of or work on the precharge pump, the air it contains must be extracted. This takes place by activating the precharge pump, rinsing and venting the front-axle circuit.

Following replacement and repair of the following parts, the DIS tester must be used for venting:

Operations:

Operations 4 ... 8 are to be performed in the order rear right, rear left, front right and front left. Exception: if only work has been performed on the precharge pump, then only front right and front left.

  1. Connect the brake fluid replacement device and switch on (The fill pressure must not exceed 2 bar)
  2. If work has been done on the precharge pump: activate the precharge pump
  3. Fully rinse the brake system Exception: if only work on the precharge pump has been carried out, only the front-axle circuit needs to be rinsed
  4. Attach the venting bottle to the vent valve
  5. Open the vent valve
  6. Start venting with the DIS tester with opened bleeder valve
  7. After completion of the venting, press the brake pedal 5 times down as far as it will go; the brake fluid that escapes must be free of bubbles
  8. Close the vent valve
  9. Remove the brake fluid replacement device

Note:

A second person is required for this task