How to Wire a Standard Automotive Relay

This article covers how to wire up a standard five pin SPDT (single pole double throw) relay. A relay can be used to boost current, turn something on/off, or reverse polarity on a trigger.

The Standard 5 pin (SPDT) relays provide 2 pins (85 & 86) to control the coil and 3 pins (30, 87 & 87A) which switch current flow between two contacts. They have both normally open and normally closed connection pins. When the coil is activated, current will be switched from the normally closed pin (87A) to the normally open pin (87). Example:

This can be used for many applications:

- Wiring up a camera to reverse light trigger

- Flipping a negative output to a positive output or vice versa

- Remote output for many aftermarket amplifiers

-Acessory power to devices requiring more current