Metra 120E5000 SPDT Relay Installation Guide

Quick Guide from the Manual

The Metra 120E5000 is a Single-Pole, Double-Throw (SPDT) relay used for high-current switching in automotive applications. Before beginning any installation, verify all items received against your invoice. If you are running a wire directly to the battery for power, it is recommended to install a 30-amp fuse in-line, close to the battery connection. Always tape off any unused wires to prevent short circuits.

About the Relay

A relay acts as a switch controlled by a voltage input rather than manual action. By sending current through the relay, you can turn a device on or off without physically touching the device.

Wiring Connections

Proper wiring technique is essential for a reliable connection:

• Strip: Strip the wires back 1/2 inch.
• Twist: Twist the wires together.
• Crimp: Insert into a crimp cap and squeeze the middle of the cap for a tight connection.

Application: Relay Turn-On

Used for high-current on/off switching (up to 30 amps), such as turning on a neon light tube or amplifier when the in-dash receiver is powered on.

• Green (86): Connect to a positive switched power source (e.g., amplifier turn-on lead).
• Red (30): Connect to a constant (unswitched) 12V power source.
• White (87): Connect to the positive lead of the device to be turned on.
• Black (85): Connect to chassis ground.
• Blue (87a): Not used (tape off).

Application: Relay Turn-Off

Used to disable a device, such as a car starter system, when an alarm is triggered.

• Green (86): Connect to the key side of the starter trigger wire.
• Red (30): Connect to the key side of the starter trigger wire.
• Black (85): Connect to the starter-disable lead from the security system.
• Blue (87a): Connect to the solenoid side of the starter wire.
• White (87): Not used (tape off).

Application: Remote Trunk Release

Allows opening the trunk using a security system remote. Requires an existing power-assisted trunk release switch.

• Green (86): Connect to a constant (unswitched) 12V power source.
• White (87): Connect to one side of the existing trunk release switch.
• Black (85): Connect to the remote output lead from the security system.
• Blue (87a): Not used (tape off).
• Note: If the trunk switch only works when the key is on, connect the Red (30) wire to the unswitched 12V power source along with the Green (86) wire.

Application: Power Door Lock System

Requires an actuator for each door and two relays to activate aftermarket power door locks via a security system remote.

• Green (86) & White (87): Connect to a constant (unswitched) 12V power source.
• Black (85): Connect to the LOCK/UNLOCK output from the security system.
• Red (30): Connect to the actuator wires.
• Blue (87a): Connect to chassis ground.

Application: Antenna Turn-On

Specific to 1981-1995 Mazda vehicles with factory-equipped power antennas. This application switches a positive signal to a negative signal.

• Green (86): Connect to the power antenna/remote wire on the new receiver.
• Red (30): Connect to the power antenna wire on the receiver wiring harness.
• Black (85) & White (87): Connect to chassis ground.
• Blue (87a): Not used (tape off).