The diagnostics will now be illustrated by using the example of an Opel Cascada 1.4i 16V Turbo, model year 2013 with a mega macs 77 diagnostic unit. This example, however, also covers vehicle models which are identical in construction. This vehicle with a turbocharger and STOP-START system has a HELLA UP28 vacuum pump with a pressure sensor on the brake booster installed.
The electric vacuum pump, or rather its functioning, is monitored by the relevant higher-level electronic control unit. Any occurring errors are stored in the control unit's error memory and can be exchanged by using a suitable diagnostic unit. Furthermore, the driver is warned about a system error by way of the display on the instrument cluster.
However, before control unit diagnostics are undertaken, it is first of all advisable to carry out a visual check on the individual system components as part of initial troubleshooting activities. In conjunction with this inspection, the pneumatic and electric connections of the vacuum pump and the condition of all other vacuum lines to the brake booster should be checked. In this way some errors can be eliminated during the control unit diagnostics.