2024 International LT Bulb Size Chart & Replacement Guide

As an ASE-certified master technician who spends plenty of time wrenching on heavy-duty commercial trucks, I know how critical proper lighting is for a 2024 International LT. Whether you are an owner-operator maintaining your own rig or a fleet manager keeping your trucks DOT compliant, knowing the right bulb sizes saves downtime.

The 2024 International LT comes heavily equipped with LED lighting from the factory on most trims, but some base fleet models still utilize replaceable halogen bulbs. Below is the comprehensive bulb size guide for your 2024 International LT.

Quick reference

Note: For International LT trucks equipped with the premium LED headlight packages, the low beam, high beam, and DRL are integrated into a single sealed housing. If the LED module fails, the entire headlamp assembly must be replaced.

LED vs halogen upgrade considerations

Upgrading your fleet model LT from halogen to LED is one of the best investments you can make for nighttime visibility and safety. However, commercial trucks utilize advanced Body Control Modules (BCMs) that monitor lighting circuits.

If you drop aftermarket LED bulbs into a halogen circuit on an International LT, the BCM may detect the lower current draw and trigger a "Bulb Out" warning on the dash, or cause the lights to flicker (hyper-flash for turn signals). To fix this, you will need CANBUS-ready LED bulbs or an external load resistor. Furthermore, ensure that any aftermarket LED headlight bulb maintains a compliant beam pattern; heavy-duty trucks have high headlight mounting points, and poorly aimed LEDs will blind oncoming traffic.

How to replace each bulb

Headlights (Low/High Beam): On halogen models, open the hood and access the rear of the headlight housing. Twist the dust cap counterclockwise, disconnect the wiring harness, and twist the H11 or 9005 bulb out. If you have the sealed LED factory headlights, individual bulbs cannot be replaced; you must swap the entire housing.

Fog Lights: Located in the lower bumper, these are easiest to reach from under the bumper. Twist the H11 bulb counterclockwise to remove. For factory LED fogs, unbolt the housing bracket.

Front Turn Signals / DRL: For halogen housings, access the turn signal socket from the rear of the headlamp assembly. Give it a quarter-turn counterclockwise to pull the 3157NA bulb.

Rear Tail / Brake / Turn / Reverse: Most commercial setups use standard 4-inch round grommet-mount lights at the rear. If they are halogen, pop the lens or housing out and replace the 3157/3156 bulb. Most 2024 LTs use sealed 4-inch LED pucks—simply pry the puck out of the rubber grommet, unplug the 3-prong pigtail, and push a new sealed unit in.

Side Markers & License Plate: Cab and sleeper side markers are usually sealed LED modules held by two screws. License plate lights are generally a simple 194 bulb protected by a plastic cover that snaps off.

Dome / Map Lights: Use a plastic trim tool to pry the clear plastic lens down. Pull the glass 194 or 578 festoon bulb straight out.

Common lighting issues for this generation

The International LT's electrical system is robust, but corrosion is the enemy of any Class 8 truck. The most common lighting issues stem from poor grounds or corroded pigtails at the rear trailer connection and tail light housings. Road salt and magnesium chloride can eat through the rear light harnesses. Always pack your electrical connectors with dielectric grease during bulb or housing replacements. Additionally, front headlamp housings on high-mileage units can suffer from condensation if the rear dust caps are not seated properly after a bulb change.

Need help diagnosing a stubborn electrical issue or replacing a complete headlamp assembly? Find a trusted shop on Repairius.