Automotive Relay 12V - 5 Pins

A relay is essentially a switch that works electrically instead of mechanically. Although there are several relay designs, those most commonly found in low-voltage automatic and marine applications are electromechanical relays that work by activating an electromagnet to pull a set of contacts to open or close a circuit. These are widely used in all electrical systems of the vehicle. Terminals on the exterior of a 4-pin mini relay are marked with numbers as shown below:

• Terminal/PIN number connection
• 85 . coil
• 86 . coil
• 87 . Normally open (no)
• 87a. Normally Closed (NC): Not present on 4-pin relays
• 30 . Common connection to NA and NC terminals

According to DIN 72552, the coil must be powered with +12V to terminal 86 and grounded through terminal 85, however, in practice, there is no difference in the way they are wired, unless you are using a relay with a integrated diode