2019 International LT Bulb Size Chart & Lighting Guide

As an ASE-certified master technician, I’ve serviced countless Class 8 trucks, and the International LT series is one of the most common heavy haulers in our bays. Proper lighting is critical when you are hauling 80,000 pounds down a dark interstate. If you’re driving or maintaining a 2019 International LT, knowing your exact bulb sizes will save you valuable downtime.

Below is your comprehensive guide to the 2019 International LT bulb sizes. Keep in mind that International heavily pushed their long-life LED headlight assemblies for the LT, but many fleet-spec trucks were still ordered with replaceable halogen capsules.

Quick Reference: 2019 International LT Bulb Sizes

Note: For OEM LED headlights and DRLs, the bulbs are not serviceable individually. The entire headlamp housing must be replaced if the internal LEDs fail.

LED vs Halogen Upgrade Considerations

Upgrading a fleet-spec halogen 2019 International LT to LED bulbs is a popular way to improve nighttime visibility and reduce maintenance intervals. However, commercial trucks have sensitive electrical systems managed by a Body Control Module (BCM).

• CANBUS Errors & Flickering: LED bulbs draw significantly less amperage than halogen bulbs. The LT’s diagnostic system may interpret this low draw as a "bulb out" condition, triggering dashboard warnings or causing the headlights to strobe/flicker. You will likely need CANBUS decoders or load resistors installed in-line with the new LED bulbs to trick the BCM.
• Housing Clearance: Heavy-duty truck headlamp housings can be tight. Upgraded LED bulbs with large external heat sinks or cooling fans may not fit behind the dust covers. Look for compact, fanless LED designs, or be prepared to use extended dust caps to keep moisture out of the assembly.
• DOT Compliance: Make sure any aftermarket LED bulb you install in a halogen housing maintains a proper beam pattern to avoid blinding oncoming traffic and to pass DOT inspections.

How to Replace Each Bulb

• Headlights (Low/High Beam): Open the hood and secure it. Access the rear of the headlamp assembly. For halogen setups, twist the dust cover counterclockwise, unclip the wiring harness, and twist the H11 or 9005 bulb out. For OEM LED housings, there are no bulbs to replace; unbolt the entire assembly from the hood and swap in a new unit.
• Front Turn Signals & DRLs: On halogen-equipped trucks, the 3157NA turn signal bulb can be accessed from the rear of the housing alongside the headlights. Twist the socket counterclockwise to remove.
• Fog Lights: Located in the lower bumper, these can easily be accessed from underneath the truck. Unplug the harness, push the retaining tabs, and twist the H11 bulb free.
• Rear Tail, Brake, Turn, & Reverse: Most 2019 LTs utilize standard heavy-duty 4-inch round sealed lights (like Truck-Lite or Grote) mounted in the rear frame bracket or mudflap hangers. Pop the light out of its rubber grommet with a flathead screwdriver and unplug the 3-prong pigtail.
• Cab Roof & Side Markers: Usually secured with two Phillips screws. If they are replaceable 194 bulbs, pull the lens off and pull the bulb straight out.
• Interior Dome/Map Lights: Carefully pry the plastic overhead lenses down with a plastic trim tool. The 211-2 festoon bulbs pull straight down out of their tension clips.

Common Lighting Issues for this Generation

The 2019 International LT is generally reliable, but its lighting systems face extreme vibrations and weather conditions.

• Corroded Pigtails: The rear 4-inch round lights are highly susceptible to road salt and magnesium chloride. If a brake or tail light fails, check the 3-prong pigtail for green corrosion before assuming the sealed LED unit is dead. Apply dielectric grease to all new connections.
• Moisture in the Headlamps: Stone chips or cracked rear dust covers can allow moisture into the headlight housings, which will rapidly burn out halogen bulbs and degrade the reflector bowls.
• Chafed Wiring: The hood harness routing on the LT can sometimes rub against the frame or hinges when opening and closing the hood over thousands of miles, leading to intermittent headlight or turn signal failures.

Need professional help tracking down an electrical gremlin or swapping a heavy-duty headlamp assembly? Find a trusted shop on Repairius.