DPDT Relay - Double Pole / Double Throw Relay

There are a total of 8 connections on this relay.
The first two connections (13 & 14) are used for the latching action of the relay and are directly connected to the relay coil.
The second two connectors (9 & 12) are internally wired to the relay contacts – when the relay is latched, both contacts will pull-in changing the output from the forth set of contacts (1 & 4) to the third set (5 & 8). (The inputs are independent of each other. You could have 12 volts on one side and a ground on the other if needed.)
The last four connectors are for your outputs and will change during the switched / un-switched state.

Hint: Imagine the relays above with a dotted horizontal line thru the center of the relay. Each side is independent of each other.

SPDT Relay - Single Pole / Double Throw Relay

Now for an easier to understand relay, the SPDT ( Single Pole / Double Throw ) relay. This is the relay that will carry the load. You want to purchase a 30/40 amp relay to make sure that your relay can carry the load thru posts 30 & 87.
The switching (latching) is performed by sending a + and – on either side of the coil as noted on posts 86 and 85. In an un-latched state, the path is from posts 30 and 87a. When latched (or switched), the path changes to 30 and 87. Simple, right?

Hint: Normally you would use a relay to pass voltage or a ground from post 30 to post 87 when switched (control a fan, fuel pump, etc.) You can change to output to a device by having a ground on post 87a and voltage on 87 ( used for power windows, liner actuators, etc.)

Reed Switch

The reed switch is simply a switch that changes poles when a magnet is held close to it. This is the same switch that you would find on alarm systems at doors and windows.
You will want to make your connections on the COMM (Common) and the NC (Normally Closed) connections. When a magnet is held close to the switch, the reed will switch from the NO (Normally Open) connection to the NC (Normally Closed) connection.

Hint: Are you confused why you would want to make your connection on the NC side of the switch? You may not be confused now, but you will when you start to wire your immobilizer. These switches are normally used where a magnetic field is always present. This is considered the normal state of the switch (where a magnet is always present). Always check continuity before wiring the switch. You want the circuit to have continuity when your magnet is placed next to the reed switch.

Momentary Switch - Normally Closed

The normally closed momentary switched will be used to momentarily break a circuit when the switch is pushed. Very simple to understand in that the switch will always complete a circuit until manually pushed by you. As long as you keep the button pushed, the circuit will be broken. When you release the button, the circuit will close.

Hint: Make sure that you purchase a NORMALLY CLOSED momentary switch!

We have the full documentation for this installation on our Documents Page if you wish to download and print.

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