An SPDT (Single Pole Double Throw) switch is used by the Bosch 5 pin relay,
Pins 85 and 86 are linked to the 12v coil, which powers the SPDT switch. Pins 30 and 87a are connected when the 12v coil is not powered. Pins 30 and 87 are connected when 12v is applied to the coil (pins 85 and 86).