Complete Guide to Automotive Relays for Vehicle Tracker Installations

Few components are as important in a tracker installation as the automotive relay. Although small and relatively simple, it plays a fundamental role in various applications, especially in vehicle immobilizer systems.

Choosing the correct relay, understanding its operation, and installing it properly are factors that directly influence the reliability of the installation.

In this complete guide, you will learn everything you need to know about automotive relays used in vehicle trackers.

What is an automotive relay?

A relay is an electromechanical switch controlled electrically.

Its purpose is to allow a low-current circuit to control another circuit with a higher capacity, without both being directly connected.

In a tracker installation, it typically acts as an intermediary between the electronic module and the commanded circuit.

This feature increases safety and protects the electronic components of the equipment.

How does a relay work?

The operation is relatively simple.

When the relay's internal coil receives electrical power, a magnetic field is created.

This field moves an internal contact that changes the state of the circuit.

When power is removed, the contact returns to its original position.

This process happens in fractions of a second.

Main applications in trackers

Relays are used in various functions.

Among the most common are:

immobilizer systems; accessory activation; auxiliary commands; vehicle automation; circuit protection.

Their use depends on the tracker's characteristics and the installation.

Understanding relay terminals

Automotive relays follow an international terminal standardization.

The most common are:

Terminal 30

Input for power or main circuit.

Terminal 85

One of the coil terminals.

Terminal 86

Second coil terminal.

Terminal 87

Normally open (NO) contact.

It is connected to terminal 30 when the coil is energized.

Terminal 87A

Present only in changeover relays.

Corresponds to the normally closed (NC) contact, connected to terminal 30 while the coil remains de-energized.

Types of automotive relays

There are several models available on the market.

The main ones are:

4-pin relay

The most used in automotive installations.

It has:

30

85

86

87

5-pin relay

Similar to the previous one, but includes terminal 87A.

Allows for applications requiring normally closed contacts.

Sealed relays

Suitable for environments subject to moisture and dust.

Widely used in heavy vehicles.

Miniature relays

Applied when space is limited.

How to choose the correct relay?

Before installation consider:

current capacity; nominal voltage; manufacturer quality; installation environment; required contact type.

Never choose a relay based on price alone.

Current capacity

Each relay has a supported current limit.

Using an undersized component can cause:

overheating; premature wear; intermittent failures; welding of contacts; loss of immobilization function.

Always respect the manufacturer's specifications.

Relay positioning

The chosen location must provide protection against:

moisture; vibration; excessive heat; impacts.

It should also facilitate future inspections.

Correct fastening

Avoid leaving the relay suspended by the harness.

Use appropriate supports.

In addition to increasing the durability of the installation, it reduces vibrations and improves the finish.

Electrical protection

Always use, when necessary:

fuses; conduits; appropriate terminals; organized harnesses.

Relay protection is part of the protection of the entire installation.

Care with hybrid and electric vehicles

Although many systems use the 12V auxiliary network, these vehicles have very sophisticated electronic architectures.

Before installing any relay:

consult technical documentation; follow manufacturer's recommendations; preserve the originality of the harness. Most common errors

Among the problems found are:

use of undersized relays; low-quality components; lack of fastening; unprotected harness; poorly executed connections; lack of documentation; lack of testing. Checklist for relay installation

Before vehicle delivery, confirm:

✔ The relay has the correct specification.

✔ Terminals were correctly identified.

✔ The harness is protected.

✔ Connections are isolated.

✔ The relay is firmly fixed.

✔ All tests have been performed.

✔ Operation has been validated.

✔ The installation has been documented.

Benefits of using quality relays

An installation performed with appropriate components provides:

higher reliability; lower failure rate; longer lifespan; electrical safety; ease of maintenance; best finish. Conclusion

The automotive relay is a simple but indispensable component for various applications in vehicle tracking systems. Understanding its operation, knowing the different types, and correctly selecting the appropriate model are fundamental steps to ensure safe, reliable, and durable installations.

In addition to using quality components, the installer must prioritize an organized assembly, protect the harness, perform complete tests, and document the installation. These precautions reduce rework, increase customer satisfaction, and strengthen the professional's reputation.

Frequently Asked Questions (FAQ)

Does every tracker use a relay?

No. It depends on the functions offered by the equipment. Systems that perform remote immobilization typically use relays or equivalent devices.

Can I use any automotive relay?

No. The component must be compatible with the voltage, current, and application specified by the manufacturer.

What is the difference between a 4 and 5-pin relay?

The 5-pin relay has a normally closed contact (terminal 87A), offering more application possibilities.

Can I install the relay anywhere in the vehicle?

No. It is ideal to protect it from moisture, excessive heat, and vibrations, as well as to facilitate future maintenance.

Is it necessary to test the relay after installation?

Yes. Before vehicle delivery, all commands must be tested to ensure correct system operation.