Relays

ISO Relays

All ISO relays are wired in this manner. Pins 85 and 86 are the control circuit for activation of the relay. When the relay is de-energized, pin 30 is connected to pin 87a. Once 85 and 86 have power and ground, the relay is then energized and pin 30is now connected to pin 87. See the ISO Relay sheet for relay pin configurations for therelay and the receptacle.

In standard ISO relay wiring, pin 86 is power for the control circuit and pin 85 is the ground for the control circuit. Pin 30 is connected to B+ for the load path and pin 87 is the power supply circuit for the load that the rely operates.

Relays are used so that high current circuits can be controlled by low current circuits. The ECM can handle the relatively low current of the relay control circuit, but not the high current flow that the load (such as the fuel pumps) carries.