2016 Peterbilt 579 Bulb Sizes

Quick reference

The 2016 Peterbilt 579, a popular choice for long-haul trucking, offers various lighting configurations that can impact bulb sizing. While many trucks came equipped with traditional halogen bulbs, some higher trim levels or later production models might feature OEM LED lighting. It's crucial to verify your truck's specific setup before purchasing replacement bulbs.

For headlights, the low beam commonly uses an H11 bulb, and the high beam an H9. However, Peterbilt offered optional LED headlight assemblies. If your 579 has the factory LED headlights, individual bulb replacement for the main beams is typically not possible, as the LEDs are integrated into the housing. Fog lights almost universally use an H10 bulb.

Many of the exterior marker and signal lights, including DRLs (Daytime Running Lights), front and rear turn signals, brake lights, tail lights, and reverse lights, often share common bulb types. The 3157 or 7443 are frequently found in these positions, with incandescent versions being standard and LED options available as OEM upgrades or aftermarket replacements. Peterbilt also offered full LED tail light assemblies on some models, again negating individual bulb replacement in those cases.

Smaller bulbs such as those for the license plate and side markers commonly utilize the 194 size, while interior dome and map lights can vary, with 921 and 194 being common. Again, LED equivalents were available from the factory or are common aftermarket upgrades.

LED vs Halogen Upgrade Considerations

Upgrading from halogen to LED bulbs in your 2016 Peterbilt 579 can offer numerous benefits, including brighter light, longer lifespan, and reduced power consumption. However, there are several key considerations to keep in mind, especially with a modern truck equipped with a CANBUS (Controller Area Network Bus) system.

CANBUS Errors: The CANBUS system monitors the electrical circuits of your truck. LED bulbs draw significantly less power than their halogen counterparts. When an LED is installed in a circuit designed for a higher-wattage halogen bulb, the CANBUS system might interpret the lower power draw as an "outage" or a fault, triggering a dashboard warning light (e.g., "bulb out" indicator) or causing hyper-flashing for turn signals. To prevent these errors, you will likely need to install CANBUS-compatible LED bulbs or load resistors (also known as decoders) in parallel with the LED bulbs. Load resistors trick the CANBUS system into seeing the same resistance as a halogen bulb, thus preventing error messages.

Adapters Needed: While many LED bulbs are designed to be "plug-and-play" replacements for halogen bulbs, some may require specific adapters to ensure a secure fit and proper electrical connection, especially in the headlight housings. Always check the fitment of any aftermarket LED bulb with your specific truck model.

Beam Pattern for Headlights: When upgrading headlight bulbs to LED, it's critical to ensure the LED bulb replicates the beam pattern of the original halogen bulb as closely as possible. Poorly designed LED headlight bulbs can create excessive glare for oncoming traffic and result in a scattered, ineffective light output. Look for LED bulbs that mimic the filament placement of their halogen equivalents to maintain proper light distribution when used in reflector housings.

How to Replace Each Bulb

Replacing bulbs on your 2016 Peterbilt 579 generally involves straightforward procedures, though access can sometimes be tight in certain areas.

• Headlights (Low/High Beam): Access to headlight bulbs is typically from the rear of the headlight assembly, often by removing a cover or cap. Twist to unlock the bulb and pull it out. Be careful not to touch the glass of new halogen bulbs, as oils from your skin can create hot spots and shorten their lifespan.
• Fog Lights: These are usually accessible from underneath the front bumper or wheel well. You may need to remove a few fasteners from a splash shield to gain access.
• DRL/Front Turn Signal: Often located within the main headlight assembly or a separate housing beside it. Access usually involves reaching behind the housing.
• Rear Turn Signal/Brake Light/Tail Light/Reverse Light: Access to these bulbs is usually from behind the tail light housing. You may need to remove a few screws or clips to remove the entire assembly, or twists the individual bulb sockets from the back of the housing.
• License Plate: Typically a single bulb located in a small housing above the license plate. Access is often by removing a small lens cover.
• Side Marker: These small bulbs are usually found within a small, easily removable lens on the side of the truck or fender.
• Interior Dome/Map Lights: Gently pry off the lens covers using a plastic trim tool to avoid marring the plastic. The bulbs are usually pushed or twisted into their sockets.

Always ensure the ignition is off and the lights are cool before attempting any bulb replacement to prevent electrical shock or burns.

Common Lighting Issues for this Generation

Owners of the 2016 Peterbilt 579 may encounter a few common lighting-related issues:

• Flickering Lights or "Bulb Out" Warnings: As mentioned, this is often related to aftermarket LED upgrades on a CANBUS system without proper load resistors or compatible bulbs.
• Corrosion in Sockets: Due to exposure to the elements, especially in heavy-duty truck applications, bulb sockets can sometimes corrode, leading to intermittent connections or complete bulb failure. Cleaning the contacts with electrical contact cleaner and a small brush can often resolve this.
• Premature Bulb Failure: Excessive vibration, common in trucking, can lead to premature failure of incandescent bulbs. Upgrading to more robust LED bulbs can help mitigate this.
• Moisture in Light Housings: Damaged seals or cracks in light housings can allow moisture to enter, leading to condensation, corrosion, and bulb failure. Inspect housings regularly and replace any that are compromised.

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