2018 International MV Bulb Sizes: Headlight, Tail, Fog & More

As an ASE-certified master technician, I know that keeping a commercial truck like the 2018 International MV properly lit is about more than just visibility—it’s about DOT compliance and safety on the job site. The 2018 MV (which succeeded the popular DuraStar series) offers a mix of traditional halogen bulbs for fleet buyers and upgraded factory LED options for premium trims.

Whether you’re managing a fleet or operating a single rig, this comprehensive guide will help you identify the exact bulb sizes you need to get your International MV back on the road safely.

Quick Reference: 2018 International MV Bulb Sizes

Below is the standard bulb size chart for the 2018 International MV. Note: Rear lighting on commercial cab-and-chassis trucks often depends on the upfitter body (e.g., box truck, dump, flatbed). The sizes below reflect standard factory-supplied chassis lighting.

Trim Level Variations: The 2018 International MV is available with a standard halogen headlight assembly (utilizing dual-beam H4 bulbs) or a premium OEM LED headlight package. If your truck has factory LEDs, the entire headlight housing is a sealed unit, and individual bulbs cannot be replaced.

LED vs Halogen Upgrade Considerations

Upgrading your halogen fleet to aftermarket LEDs is highly popular for the International MV, as it greatly improves nighttime visibility on poorly lit highways. However, commercial truck electrical systems require a bit of extra care:

• CANBUS Errors and Hyper-Flashing: The MV uses a multiplexed electrical system (Diamond Logic). If you swap standard 3157 halogen turn signals for LEDs, the system will detect a drop in resistance and cause hyper-flashing or throw a "bulb out" warning on the dash. You will need CANBUS-ready LED bulbs or an inline load resistor.
• Headlight Housing Space: Commercial truck headlight housings can be tight around the rear dust cover. When upgrading an H4 halogen to LED, ensure the LED bulb has a compact cooling fan or braided heatsink that fits behind the factory moisture seal.
• DOT Compliance: Make sure any aftermarket LED headlight bulbs are DOT-compliant and properly aimed so they do not blind oncoming traffic, which is a frequent trigger for roadside commercial vehicle inspections.

How to Replace Each Bulb

Handling bulb replacements on the MV is generally straightforward, designed to minimize fleet downtime.

• Headlights (Low/High Beam): Tilt the truck hood forward. Reach behind the composite headlight assembly. Remove the rubber dust boot, unplug the wire harness, unclip the retaining wire, and pull the H4 bulb out. Avoid touching the new halogen glass with your bare fingers.
• Front Turn Signals & DRLs: Also accessed from behind the headlight assembly with the hood tilted. Twist the bulb socket counterclockwise and pull it out.
• Fog Lights: Located in the lower bumper. Reach underneath or behind the bumper, unplug the H11 harness, and give the bulb a quarter-turn counterclockwise to remove.
• Cab Clearance / Side Markers: Many factory clearance lights on the MV are sealed LED units requiring full housing replacement if they fail. If equipped with standard lenses, remove the two Phillips screws, pull the lens, and pull the 194 bulb straight out of its socket.
• Rear Lighting (Brake/Tail/Turn/Reverse): Since the MV is commonly upfitted, your rear lights might be round 4-inch or oval 6-inch sealed LED units housed in rubber grommets. For these, simply pry the light out of the grommet and unplug the 3-prong pigtail. If you have the factory chassis-cab temporary lights, they use standard 3157/3156 bulbs accessed by removing the Phillips screws on the lens.
• Dome/Map Lights: Carefully pry the plastic interior lens cover off with a flathead screwdriver or trim tool to access the festoon-style 578 bulb.

Common Lighting Issues for this Generation

While the 2018 International MV is a rugged workhorse, technicians frequently see a few specific lighting issues. First, the Diamond Logic electrical system is highly sensitive to corrosion. Corroded ground wires near the frame rails often cause flickering rear tail lights or phantom dashboard warnings. Always use dielectric grease on rear connections, especially in states that salt their winter roads. Second, moisture intrusion in the front halogen composite headlight assemblies can cause premature H4 bulb failure. If you are replacing bulbs constantly, inspect the housing for hairline cracks or a torn rear dust boot.

When it comes to maintaining your commercial truck, professional diagnostics are sometimes necessary to keep you DOT-compliant. Find a trusted shop on Repairius.