2019 Peterbilt 389 Bulb Size Guide

Quick Reference Bulb Size Chart

Note: Higher trim levels of the 2019 Peterbilt 389 may feature factory-installed LED systems for some of these locations, particularly the headlights and brake/tail lights. Always double-check your existing bulbs before purchasing replacements.

LED vs. Halogen Upgrade Considerations

Upgrading your 2019 Peterbilt 389's factory halogen bulbs to LED can offer significant advantages in brightness, lifespan, and energy efficiency. However, there are a few key factors to consider before making the switch, especially for a heavy-duty truck like the 389.

• CANBUS Errors: The 389's computer system (CANBUS) monitors the electrical current drawn by the lighting system. Since LEDs draw significantly less power than halogen bulbs, the system might mistakenly register this as a "bulb out" error, causing a warning light on your dash or causing the bulb to flicker or not work at all. To prevent this, you'll likely need to install "CANBUS-ready" LED bulbs or add an external resistor to the circuit to mimic the load of a halogen bulb.
• Adapters and Fitment: While most LED replacement bulbs are designed to be "plug-and-play," the physical housing and connectors on the Peterbilt 389 can sometimes present a challenge. For headlights and fog lights, ensure the LED bulb's heat sink or fan has enough clearance behind the assembly. You may also need a specific wiring harness adapter to connect the new LED bulb to the factory plug.
• DOT Compliance: When upgrading headlights, it's crucial to use DOT-approved LED bulbs that are designed to replicate the beam pattern of the original halogen bulb. This ensures you are not blinding oncoming traffic and that the road is properly illuminated.

How to Replace Each Bulb

Replacing the bulbs on your 389 is generally straightforward, but here are some tips for each location:

• Headlights (Low and High Beam): Access is typically through the back of the headlight assembly. You may need to remove a dust cover. The bulbs usually twist and lock into place.
• Fog Lights: These are located in the front bumper. Access may be from underneath the bumper or by removing a small panel.
• Turn Signals, Brake, and Tail Lights: These are usually housed together. You'll need to remove the lens cover (typically held by a few screws) to access the bulbs.
• License Plate Light: The housing for this small bulb often has a simple clip or a couple of screws holding it in place.
• Side Markers: Similar to the license plate light, these are typically easy to access by removing a small lens cover.
• Interior Dome/Map Lights: The clear plastic cover for these lights can usually be gently pried off with a flathead screwdriver to reveal the bulb.

Common Lighting Issues for this Generation

The Peterbilt 389 is a workhorse, and its lighting system is generally robust. However, some common issues can arise:

• Vibration Damage: The constant vibration of a commercial truck can shorten the life of standard incandescent bulbs. This is a strong argument for upgrading to more durable LED bulbs.
• Connector Corrosion: The electrical connectors for the lights, especially those exposed to the elements, can corrode over time, leading to intermittent or failed lights. Regularly inspecting and cleaning these connectors can prevent problems.
• Voltage Fluctuations: Heavy-duty trucks can sometimes experience voltage spikes or drops, which can also damage bulbs. If you find yourself replacing bulbs frequently, it may be worth having your truck's electrical system checked.

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