Did Ya know the difference? 4-pin relay / 5-pin relay
For years I have known about relays. Use them for fan, headlights, horn----in fact anything that has a high current draw, where you don't want the high current carrying wires inside the passenger compartment, or else don't want the high current carrying wires to travel too far, which causes a voltage drop. You mount the relay on the firewall in the engine compartment, route the heavy wire from the battery to the relay, then from the relay to the high current device. Then you have a relatively small wire, carrying a low current that runs from inside your car where the switch is located out through the firewall to the relay. When you turn on the switch inside the car, this "small" current flows through an electromagnet inside the relay, then to ground, which pulls the contacts inside the relay closed, and lets high current from the battery flow through the device which you want to power up.
Now I realize that this is pretty basic stuff, and that this requires 4 pins on the relay for wire connections. Last week I bought a relay, and when I got it home, it had 5 pins----a real head scratcher. After a bit of internet searching, I found out something interesting. A 4-pin relay either is "on", letting current flow, or else its "off" and not letting current flow.
A 5 pin relay, lets current flow in either of 2 different paths. Thats what the extra "pin" is for. When the relay is in the "off" position, it lets current flow out through one of the pins-----when the relay is switched to the "on" position, it switches the current to flow through the other pin, acting like a 2 position selector switch. If one of the pins is not hooked up, then the relay acts the same as a 4 pin relay, giving either "on" or "off".
This is kind of neat, and I really never knew this before.
