2018 Volvo VNL Bulb Size Guide: Headlight, Tail, Fog & More

The 2018 model year was a massive milestone for the Volvo VNL. Marking the introduction of a completely redesigned aerodynamic body and overhauled electrical systems, this Class 8 workhorse brought major improvements to driver visibility. While many fleets opted for the stunning new OEM LED headlight packages, there are still plenty of halogen-equipped models on the road.

As an ASE-certified master technician, I know how critical lighting is when you are hauling freight through the night. Whether you are dealing with a burnt-out halogen bulb, upgrading your fleet to LEDs, or trying to figure out which marker light size you need, this guide covers everything you need to know about the 2018 Volvo VNL lighting system.

Quick reference

Note: The 2018 Volvo VNL heavily utilized sealed LED assemblies for higher trims (VNL 760, 860). If your truck has the OEM LED package, the bulbs are not serviceable, and the entire housing must be replaced. The sizes below apply to base model halogen trims and standard incandescent setups.

LED vs halogen upgrade considerations

Upgrading a heavy-duty commercial truck from halogen to LED is one of the best investments an owner-operator can make. However, the 2018 Volvo VNL uses a highly advanced lighting control module (LCM) that is extremely sensitive to voltage changes.

If you are swapping standard H11 halogen headlight bulbs for aftermarket LEDs, you must ensure the LED bulbs are CANBUS compatible. Because LEDs draw significantly less power, the truck’s computer may think the bulb is burnt out, resulting in dash warnings or rapid flickering. In many cases, installing an anti-flicker decoder (load resistor) inline with the H11 LED kit is required to keep the system happy. Also, keep in mind that the dust covers on the back of the VNL headlight housings must be properly sealed after installing bulky LED heatsinks; otherwise, moisture will ruin the assembly.

How to replace each bulb

• Headlights (Low/High Beam): Tilt the hood forward. The headlight housings on the 2018 VNL are easily accessible from the rear. Twist off the round dust caps. Push down on the locking tab of the electrical connector, unplug it, and twist the H11 bulb counter-clockwise to remove it. Avoid touching the glass of the new halogen bulb with your bare hands.
• Fog Lights: These are accessible from underneath the front bumper. A simple quarter-turn removes the H11 bulb. Keep the wiring harness tucked up safely away from road debris.
• Turn Signals & Markers: Front turn signals are located inside the main headlight housing. Side markers (often 194 bulbs) are located along the aerodynamic fairings and can usually be popped out with a plastic trim tool.
• Rear Lighting (Tractor): The brake, tail, reverse, and rear turn signals on the tractor are typically housed in heavy-duty rubber grommets or bolt-on brackets. If they are standard incandescent 3157 bulbs, remove the housing screws to access the socket. However, many fleets use standard sealed 4-inch round or oval LED modules—in this case, simply unplug the 3-prong pigtail, push the old module out of the grommet, and push a new one in.
• Cab/Sleeper Dome Lights: Use a thin pry tool to pop the plastic lenses off the interior roof consoles. Swap in a crisp white LED 194 or festoon bulb for much better visibility during downtime.

Common lighting issues for this generation

The 2018 VNL's biggest lighting issue involves the complex LED DRL strips in the premium headlight assemblies. Over time, these integrated "V-shape" daytime running lights can suffer from diode burnout. Unfortunately, these strips are not individually replaceable; the entire headlight assembly must be swapped out, which can be costly.

Additionally, we often see condensation build-up inside the headlight housings if the rear dust caps are lost or not seated correctly after a bulb change. Always double-check your seals. Lastly, check the chassis wiring harnesses near the rear drive axles; road salt and vibration frequently cause corrosion at the rear tail light pigtails, leading to intermittent brake or turn signal failures.

If you are dealing with complex wiring gremlins, CANBUS faults, or need professional upgrades, don't leave your rig stranded. Find a trusted shop on Repairius.