Capacitor box: EPS 12 V

The capacitor box is installed in the right-hand wheel arch. When EPS is used in conjunction with Integral Active Steering, the EPS unit is supplied with power via the capacitor box.

This creates a relationship between engine and transmission.

Fig 1: Identifying Capacitor Box And Pin Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The voltage supply via the capacitor box is protected by another fuse.

The ignition capacitor damps the ripple in the vehicle voltage. This ripple is generated by the alternator (3-phase).

The EPS control unit uses a dedicated line to diagnose the ripple in the vehicle voltage.