# 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch

**Automotive Wiring Harness Kit with Relay, Diode & On/Off Switch - 12V 40A, 5-Pin**

A complete 4-piece automotive wiring kit designed for clean, reliable vehicle electrical installations. Everything you need to wire up accessories, GPS trackers, lighting, power antennas, and more - all in one package.

**What's Included:**

**12V 40A Automotive Relay with Diode**

-   5-pin relay with labeled, color-coded wires for easy identification
-   Diode included to protect against voltage spikes and back-EMF
-   Harness socket included - handle the female socket carefully during installation to avoid damage

**Wiring Harness**

-   Adapter with black head connector
-   Supports power, illumination, and power antenna connections
-   Designed for clean, secure integration into vehicle electrical systems

**On/Off Switch**

-   Simple toggle switch for manual control of connected accessories

**Why This Kit?** Color-coded wires and labeled connections take the guesswork out of installation. The included diode protects your vehicle's electrical system from relay feedback, and the harness adapter covers the three most common automotive wiring needs - power, illumination, and antenna - in a single connector.

**Ideal For:**

-   Hardwired GPS tracker installations
-   Auxiliary lighting & accessory wiring
-   Power antenna connections
-   12V accessory control circuits
-   DIY automotive electrical projects

**Key Specs:**

-   Voltage: 12V DC
-   Relay amperage: 40A
-   Relay type: 5-pin with labeled color wires
-   Includes: Relay, diode, wiring harness adapter, on/off switch
-   Made in the USA

## Details

- **Price:** 14.0 USD
- **Vendor:** Spy Spot GPS
- **Tags:** Accessories, Hardwired Tracker

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 14.00 USD | In stock |

## Images

- 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch
- 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch
- 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch
- 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch
- 12V 40A Automotive Relay Kit - Wiring Harness & On / Off Switch

## Additional Information

### Technical Specifications

#### Core Technical Specifications

- **Voltage:** 12V DC
- **Amperage:** 40A
- **Relay Configuration:** 5-pin configuration with labeled, color-coded wires
- **Origin:** Made in the USA

#### Component Details & Integrations

- **Relay Protection:** Integrated diode to safeguard vehicle electronics against voltage spikes and back-EMF.
- **Wiring Harness Adapter:** Features a black head connector supporting power, illumination, and power antenna connections.
- **Manual Control:** A simple toggle on/off switch for manual accessory control.

### Features

- UPGRADE YOUR VEHICLE'S ELECTRICAL SYSTEM WITH THIS COMPLETE 4-PIECE 12V 40A AUTOMOTIVE RELAY KIT: It includes a premium 5-pin relay, heavy-duty wiring harness, integrated protective diode, and manual on/off toggle switch.
- SAFEGUARD SENSITIVE ELECTRONICS FROM ACCIDENTAL DAMAGE: The integrated diode acts as a shield against hazardous voltage spikes and back-EMF, providing ultimate circuit protection for your computer systems and connected accessories.
- ENJOY FOOLPROOF INSTALLATION WITH EASY COLOR-CODED WIRES: Pre-labeled, color-coded lines and a multi-use harness adapter take the guesswork out of wiring power, illumination, and power antennas for a clean, pro-level look.
- UNLEASH POWERFUL CONTROL OVER DEMANDING 12V DC CIRCUITS: This robust 40A system is engineered to seamlessly handle high-current loads, making it ideal for hardwired GPS tracking, auxiliary LED off-road lights, and custom DIY setups.
- EQUIP YOUR VEHICLE WITH AMERICAN-MADE CRAFTSMANSHIP TODAY: Click add to cart to secure this durable, USA-made wiring kit and confidently complete your next automotive project with reliable, professional components.

### About This Item

#### Complete 4-Piece Automotive Wiring Solution

Upgrade your vehicle's electrical system with the SPY SPOT 12V 40A Automotive Relay Kit. This comprehensive package includes a premium 5-pin automotive relay, a protective diode, a heavy-duty wiring harness with an adapter head, and a manual on/off toggle switch. It provides everything required for clean, professional, and reliable electrical installations without the hassle of sourcing separate components.

#### Advanced Electrical System Protection

Engineered for safety, this kit features an integrated diode that acts as a shield for your vehicle's sensitive electronics. The diode safeguards against hazardous voltage spikes and back-EMF feedback that naturally occurs when relays cycle on and off. Drive with total peace of mind knowing your vehicle's computer systems and connected accessories are fully protected.

#### Color-Coded & Stress-Free Installation

Take the guesswork out of complex automotive wiring. The 5-pin relay socket comes equipped with pre-labeled, color-coded wires for fast and foolproof identification during setup. The sturdy wiring harness adapter utilizes a centralized black head connector designed to cleanly manage the three most common automotive functions: power, illumination, and power antenna lines.

#### Versatile 12V Control Application

Boasting a robust 12V DC voltage rating and a high-capacity 40A amperage threshold, this relay kit handles demanding circuits with ease. It is the ultimate tool for hardwiring GPS tracking units, powering up auxiliary LED off-road lighting, wiring power antennas, managing 12V accessory circuits, or completing custom DIY automotive modifications.

#### Premium American Craftsmanship

Built to last and proudly made in the USA, this kit is constructed using high-quality components engineered to withstand daily vehicular vibration and temperature fluctuations. It offers a perfect fit for a wide range of cars, trucks, and SUVs.

### Item Highlight

- Complete 12V 40A 5-PIN Relay Kit
- Features Built-in Spike Protection
- Simple Color-Coded Installation
- Controls GPS Trackers & Lights

### Installation & Setup

#### Installation & Setup Guide

#### Safety First

Before starting, turn off your vehicle's engine and **disconnect the negative (-) battery terminal** to prevent accidental short circuits or electrical shocks.

#### Component Overview

- **5-Pin Relay & Socket:** The main control switch that handles high-current power safely.
- **Wiring Harness Adapter:** The main wire bundle with a black connector head.
- **On/Off Toggle Switch:** The manual switch you will mount inside your dashboard.
- **Integrated Diode:** Pre-wired to protect your vehicle’s sensitive electronics from power spikes.

#### Step-by-Step Wiring Diagram

Follow the color-coded and labeled wires on your harness socket to make the connections:

#### 1. Main Power Connections

- **Red Wire:** Connect directly to the **Positive (+) battery terminal** or a constant 12V power source (use an inline fuse for safety).
- **Black Wire:** Connect to a clean, unpainted metal part of the vehicle chassis for a solid **Ground (-)**.

#### 2. Trigger Switch Connections

- **Blue Wire:** Route this wire into the vehicle cabin and connect it to one side of the included **On/Off Toggle Switch**.
- **Switch Power:** Connect the other side of the Toggle Switch to an ignition-switched 12V source (so the accessory only works when the car is on).

#### 3. Accessory Connections (Choose based on your setup)

- **White Wire:** Connect to your target accessory (e.g., Hardwired GPS Tracker, auxiliary lights, or power antenna).
- **Yellow/Secondary Wire:** (Optional) Connect to your vehicle's illumination circuit if your accessory requires a dimming or backlight trigger.

#### Final Setup & Testing

1. **Mount the Relay:** Securely mount the relay housing under the hood or dashboard using a screw or zip tie, ensuring it faces downward to prevent water buildup.
2. **Reconnect Battery:** Reconnect your vehicle's negative (-) battery terminal.
3. **Test Operation:** Flip the manual toggle switch to verify that your connected accessory turns on and off smoothly.

#### 🛠️ Need Help? Find a Professional Installer

If you prefer not to handle the hardwiring yourself, we have you covered. Once you have purchased your automotive relay kit online, you can coordinate with an authorized professional to get it up and running safely.

Use our interactive locator map to find a certified technician near you:

👉[Find an Authorized Spy Spot Installer Near You](https://spy-spot.com/pages/installers)

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> Source: [Spy Store : The Best Equipment for Tracking and Surveillance](https://spy-spot.com/products/12v-40a-automotive-relay-kit-wiring-harness-diode-switch)
> Updated: 2026-08-27