The Diode Dynamics Add-On Fog Light Harness is a versatile solution for integrating fog lights into a vehicle without requiring extensive modifications. This guide provides a detailed breakdown of the installation process, based on the official documentation provided by Diode Dynamics. The harness is designed to mimic the behavior of factory-installed fog lights, allowing them to activate automatically when the headlights are turned on and the fog light switch is engaged. The installation involves routing the wiring, connecting the power and activation signals, and installing a switch in the vehicle cabin. This article outlines each step of the process and highlights key functional notes to ensure a successful and safe installation.
Overview of the Add-On Fog Light Harness
The Diode Dynamics Add-On Fog Light Harness is intended for vehicles that do not have factory fog lights or for users who want to add a second fog light system. The harness includes a wiring solution that connects to the vehicle’s existing electrical system, ensuring that the fog lights operate in harmony with the vehicle’s lighting functions. The installation guide outlines two primary methods for integrating the fog light system: (1) adding a new switch to the vehicle and (2) using an existing OEM upfitter or auxiliary switch. Both methods require careful routing of the harness, proper grounding, and correct connection of activation and deactivation signals.
Installation Tools and Materials
Before beginning the installation, ensure that you have the following tools and materials on hand:
- Basic wiring tools (wire strippers, crimping tool, soldering iron if necessary)
- A multimeter for testing electrical connections
- Electrical tape and heat shrink tubing
- Mounting hardware for the fog lights and switch
- The Diode Dynamics Add-On Fog Light Harness kit (SKUs DD4109, DD4110, DD4111, DD4112, DD4113)
It is important to work in a well-lit, clean environment to avoid damaging the wiring and to ensure a secure and professional installation. Additionally, the vehicle should be parked on a level surface, and all tools should be organized for easy access during the installation process.
Step-by-Step Installation Process
Step 1: Park the Vehicle
Begin by parking the vehicle 25 feet away from a wall or garage door on a level surface. This distance is optimal for aiming the fog lights correctly later in the installation. Ensure the vehicle is turned off and the key is removed to prevent accidental activation of the electrical system during the process.
Step 2: Measure Mounting Height
Measure the distance from the ground to the center of the fog light on your vehicle. This measurement is referred to as the mounting height. It is crucial for determining the correct position of the fog light beam on the wall during the aiming process.
Step 3: Mark Mounting Height on the Wall
Using tape, mark the mounting height on the wall or garage door. This will serve as a reference point for aligning the fog light beam. The tape should be placed at the exact height of the fog light’s center point.
Step 4: Add Cutoff Line
Below the first mark, add another piece of tape four inches lower. This second mark represents the fog light cutoff line. The top of the fog light beam should align with this line to ensure that the light is aimed correctly and does not cause glare or blind spots for oncoming traffic.
Step 5: Aim the Fog Lights
With the fog lights installed, aim them so that the top of the beam pattern aligns with the cutoff line. This ensures that the fog lights illuminate the road ahead without causing excessive glare. Repeat this step for both sides of the vehicle.
Step 6: Route the Wiring Harness
The next step involves routing the wiring harness. Begin by running the harness near the fuse box under the hood. This ensures that the wiring follows a path similar to the factory wiring, minimizing the risk of interference or damage. Route the output wires to the fog light location on each side of the vehicle. The switch wire should be run into the vehicle cabin on the driver’s side, where it will be connected to the fog light switch.
Avoid routing the wiring through areas that are subject to heat buildup or moving parts. This includes areas near the exhaust system, engine components, or under the vehicle where the wiring could be exposed to dirt or moisture.
Step 7: Connect Battery Leads
Once the wiring is properly routed, connect the positive (VB) and negative (G) battery wires to the vehicle’s battery or to the main power terminals near the fuse box. These connections provide the power source for the fog light system. Ensure that the connections are secure and insulated to prevent short circuits or electrical interference.
Step 8: Connect Activation Wire
The activation wire (DW) must be connected to an appropriate signal to enable the fog lights. It is important to note that this wire should not be connected directly to a constant 12V power source or to an ignition power source. Doing so would allow the fog lights to be activated at any time, regardless of the vehicle’s status. Instead, the activation wire should be connected to a signal such as the sidemarker or low beam signal. This ensures that the fog lights turn on automatically when the parking lights or low beams are activated.
Step 9: Connect Deactivation Wire
The deactivation wire can be used to disable the fog lights when 12V is applied. This feature is optional but can be useful for users who want additional control over the fog light system. If used, ensure that the deactivation wire is connected to a reliable 12V source that can be toggled independently of the activation signal.
Step 10: Connect Switch Input Wire
The switch input wire (S) should be connected to the fog relay. This connection allows the fog light switch to control the activation of the fog lights. Inside the vehicle cabin, connect the switch wires to the switch, ensuring that the wire colors are aligned as shown in the installation guide. Provide ground to the fog light switch using the included grounding wire (SG). This ensures that the switch operates correctly and safely.
Step 11: Mount the Fog Light Switch
Identify an unused area of the dash where the fog light switch can be mounted. Install the switch securely in this location, ensuring that it is easily accessible to the driver. Once mounted, test the switch to confirm that it functions correctly and that the fog lights respond as expected.
Step 12: Connect Output Wires to Lights
Finally, connect the output wires to the fog light on each side of the vehicle. Ensure that the connections are secure and that the wiring is properly insulated. Once all connections are made, secure the wiring using zip ties or clips to prevent it from moving or coming into contact with other components.
Step 13: Test for Function
With all wiring connected, test the fog light system to ensure that it functions as intended. Turn on the vehicle’s headlights and verify that the fog lights activate when the fog light switch is engaged. Test the system under various conditions, including low beam, parking lights, and headlight activation, to confirm that the fog lights behave consistently.
Functional Notes and Safety Considerations
The Diode Dynamics Add-On Fog Light Harness is designed to provide a reliable and safe fog light system for U.S. vehicles. However, there are several functional notes and safety considerations that should be reviewed before and after installation:
Activation and Deactivation Signals: The activation wire should be connected to a signal such as the sidemarker or low beam signal. This ensures that the fog lights turn on automatically when the parking lights or low beams are activated. The deactivation wire can be used to disable the fog lights when 12V is applied, but it is optional and should be used with caution.
Grounding and Power Connections: All grounding and power connections must be secure and properly insulated to prevent short circuits or electrical interference. Avoid connecting the activation wire directly to constant 12V power or to an ignition power source, as this could allow the fog lights to be activated at any time.
Wiring Route and Placement: The wiring should be routed along the factory wiring path to minimize the risk of damage or interference. Avoid areas that are subject to heat buildup or moving parts, and ensure that the wiring is properly secured to prevent it from coming into contact with other components.
Switch Installation and Mounting: The fog light switch should be mounted in a secure and accessible location on the dash. Ensure that the switch is properly grounded and that all connections are secure and insulated.
Testing and Verification: After installation, test the fog light system under various conditions to confirm that it functions as intended. This includes testing the system with the headlights on, the fog light switch engaged, and the vehicle in operation.
Legal Compliance: Fog lights must comply with U.S. Department of Transportation (DOT) and Society of Automotive Engineers (SAE) regulations. Ensure that the fog lights are properly aimed and that the system does not cause excessive glare or blind spots for oncoming traffic.
Warranty and Support: The Diode Dynamics Add-On Fog Light Harness is backed by a warranty and customer support. If any issues arise during or after installation, contact Diode Dynamics for assistance.
Conclusion
The Diode Dynamics Add-On Fog Light Harness is a reliable and user-friendly solution for adding fog lights to a vehicle. By following the installation guide provided, users can integrate the fog light system into their vehicle without requiring extensive modifications or electrical knowledge. The harness is designed to work seamlessly with the vehicle’s existing lighting system, allowing the fog lights to activate automatically when the headlights are turned on and the fog light switch is engaged. The installation process involves routing the wiring, connecting the power and activation signals, and installing a switch in the vehicle cabin. With careful attention to the steps outlined in the guide, users can ensure a safe and successful installation that enhances the visibility and safety of their vehicle.