As the owner of a 1999 Peterbilt 379, you know the importance of having a reliable and well-maintained vehicle. One essential component of any vehicle is the headlights. Without proper functioning headlights, it can be extremely dangerous to drive, especially during nighttime or low visibility conditions. In this article, we will provide you with a comprehensive guide on the headlight wiring diagram of your 1999 Peterbilt 379. We will cover the wiring diagram, frequently asked questions, and provide some troubleshooting tips.
Wiring Diagram
Before we dive into the details, it is important to understand what the wiring diagram is and how it works. The wiring diagram is a complete schematic representation of the electrical system of your Peterbilt 379. It provides information on the function of different electrical components, their location, and the wiring connections between them. Understanding the wiring diagram is crucial when it comes to repairing or troubleshooting any electrical issue.
The headlight wiring diagram of your 1999 Peterbilt 379 consists of several components. The first component is the headlight switch, which controls the on and off function of the headlights. The second component is the dimmer switch, which controls the brightness of the headlights. The third component is the headlight relay, which provides power to the headlights. Finally, the fourth component is the headlights, which are the output devices that emit light.
The wiring connections between these components are as follows:
| Component | Wire Color | Wiring Connection |
|---|---|---|
| Headlight Switch | Black | Ground |
| Red | 12 Volt Input | |
| Yellow | High Beam Output | |
| Blue | Low Beam Output | |
| Dimmer Switch | Grey | 12 Volt Input |
| Orange | Low Beam Output | |
| Pink | High Beam Output | |
| Headlight Relay | Black | Ground |
| Green | Low Beam Trigger | |
| White | High Beam Trigger | |
| Headlights | Blue | Low Beam Input |
| Yellow | High Beam Input |
Headlight Switch
The headlight switch is the first component in the headlight wiring diagram of your 1999 Peterbilt 379. It is responsible for turning the headlights on and off. The headlight switch has four wires: black, red, yellow, and blue. The black wire is the ground wire, and it connects to the vehicle’s chassis. The red wire is the 12-volt input wire, and it receives power from the vehicle’s battery. The yellow wire is the high beam output wire, and it connects to the high beam headlight. The blue wire is the low beam output wire, and it connects to the low beam headlight.
When you turn the headlight switch on, it sends power to the headlight relay, which then provides power to the headlights. The headlight switch also controls the dimmer switch, which we will discuss in the next section.
Dimmer Switch
The dimmer switch is responsible for adjusting the brightness of the headlights. It has three wires: grey, orange, and pink. The grey wire is the 12-volt input wire, and it receives power from the headlight switch. The orange wire is the low beam output wire, and it connects to the low beam headlight. The pink wire is the high beam output wire, and it connects to the high beam headlight.
When you adjust the dimmer switch, it sends a signal to the headlight relay to switch between the low and high beams. The headlight relay then provides power to the appropriate headlight, depending on the switch’s position.
Headlight Relay
The headlight relay is responsible for providing power to the headlights. It has three wires: black, green, and white. The black wire is the ground wire, and it connects to the vehicle’s chassis. The green wire is the low beam trigger wire, and it connects to the headlight switch’s low beam output wire. The white wire is the high beam trigger wire, and it connects to the headlight switch’s high beam output wire.
When the headlight switch is turned on, it sends power to the headlight relay. The headlight relay then receives a signal from the dimmer switch to switch between low and high beams. Finally, the headlight relay provides power to the appropriate headlight, depending on the switch and dimmer switch’s position.
Headlights
The headlights are the output devices that emit light. There are two headlights in your 1999 Peterbilt 379: one for the low beam and one for the high beam. The low beam headlight connects to the blue wire in the headlight switch, the orange wire in the dimmer switch, and the blue wire in the headlight relay. The high beam headlight connects to the yellow wire in the headlight switch, the pink wire in the dimmer switch, and the yellow wire in the headlight relay.
FAQ
How do I troubleshoot my Peterbilt 379’s headlights?
If your Peterbilt 379’s headlights are not working correctly, there are several steps you can take to troubleshoot the issue. The first thing to check is the headlight bulbs. If you notice that one or both of the bulbs are burned out, replace them with new ones. If the bulbs are not the issue, check the fuses and relays associated with the headlights. If any of these components are faulty, they can cause issues with the headlights. Finally, check the wiring connections between the various components, as loose or corroded connections can cause electrical issues.
What size headlight bulbs does my Peterbilt 379 use?
Your 1999 Peterbilt 379 uses a 9007 headlight bulb for both the low and high beams. Make sure to purchase bulbs that are specifically designed for your Peterbilt 379 to ensure proper compatibility and performance.
Can I upgrade my Peterbilt 379’s headlights?
Yes, you can upgrade your Peterbilt 379’s headlights to improve visibility and lighting performance. LED and HID headlights are popular choices for upgrading, as they provide brighter and more consistent lighting than traditional halogen bulbs. However, it is important to check your state’s laws and regulations regarding headlight upgrades, as some states have restrictions on the type of headlights that are allowed.
Troubleshooting Tips
If you are experiencing issues with your Peterbilt 379’s headlights, here are some troubleshooting tips:
- Check the headlight bulbs to ensure they are not burned out.
- Inspect the fuses and relays associated with the headlights to ensure they are functioning correctly.
- Check the wiring connections between the various components to ensure they are not loose or corroded.
- If you have upgraded your headlights, make sure they are properly installed and configured to avoid any electrical issues.
- If all else fails, consult a professional mechanic or electrician to diagnose and repair the issue.
By following these troubleshooting tips and understanding the headlight wiring diagram of your 1999 Peterbilt 379, you can help ensure that your headlights are functioning at their best and keep yourself safe on the road.
