2020 Ram 3500 Bulb Sizes (Headlight, Tail, Fog)

Quick reference

The 2020 Ram 3500 offers a range of lighting options, from traditional halogen systems to advanced OEM LED setups. Understanding your specific configuration is crucial for any bulb replacement or upgrade. Ram introduced LED headlights and taillights as an option on higher trim levels, particularly the Laramie, Longhorn, and Limited trims. If your truck has the premium LED headlight option, the low beams, high beams, and often the DRLs are integrated LED units that are not designed for bulb replacement. For these, the entire housing would need to be replaced in case of failure. Halogen setups, common on Tradesman and Big Horn trims, utilize replaceable bulbs.

LED vs Halogen upgrade considerations

Upgrading your 2020 Ram 3500 from halogen to LED bulbs can significantly improve visibility and modernize the look of your truck. However, there are several key points to consider to avoid issues:

CANBUS Errors: Modern vehicles like the 2020 Ram 3500 utilize a Controller Area Network (CANBUS) system to monitor various electrical components, including lighting. When you replace a halogen bulb with an LED, the lower power draw of the LED can trick the CANBUS system into thinking the bulb is out, triggering "bulb out" warnings on your dash. To counteract this, you'll often need CANBUS-compatible LED bulbs or separate load resistors (decoders) wired into the circuit. Without these, you might experience hyper-flashing turn signals, dashboard warnings, or even flickering lights.

Adapters Needed: While many aftermarket LED bulbs are designed for "plug-and-play" installation, some may require additional adapters to properly seat into the factory housing or connect to the OEM wiring harness. This is particularly true for headlight and fog light conversions. Ensure any LED kit you purchase specifies compatibility with your 2020 Ram 3500 and includes any necessary adapters.

Beam Pattern: When upgrading headlights or fog lights to LED, pay close attention to the beam pattern. Poorly designed LED bulbs can create glare for oncoming drivers or produce an unfocused light pattern, reducing your effective visibility. Look for LED bulbs that mimic the halogen filament's position to ensure a proper beam pattern when installed in reflector housings. Projector-style headlights are generally more forgiving with LED upgrades.

How to replace each bulb

Replacing bulbs on your 2020 Ram 3500 generally isn't overly complex, but some locations require a bit more effort.

• Low Beam/High Beam (Halogen): Access is usually from behind the headlight assembly in the engine bay. Twist and remove the old bulb, disconnect the electrical connector, and install the new bulb in reverse order. Be careful not to touch the glass of the new halogen bulb.
• Fog Light: Often accessed from underneath the front bumper or by removing inner fender liner fasteners. Twist the bulb out of the housing.
• DRL/Front Turn Signal: Access by reaching behind the headlight assembly or, in some cases, by removing the entire headlight unit for better access. Twist to remove the bulb socket.
• Rear Turn Signal/Brake Light/Tail Light/Reverse Light: Typically accessed by opening the tailgate and removing a few screws or clips that hold the entire taillight assembly in place. Once the assembly is removed, bulbs twist out from the back.
• License Plate: Usually involves removing a couple of screws that secure the lens cover. The bulb then pulls straight out.
• Side Marker (Front/Rear): Often accessed by twisting out the bulb socket from the back of the housing. Some may require popping off a small lens cover.
• Dome/Map Light: Use a plastic trim removal tool to carefully pry down the lens cover. Bulbs simply pull out or twist out, depending on the type.

Always consult your owner's manual for specific instructions and diagrams for your vehicle.

Common lighting issues for this generation

While the 2020 Ram 3500 is a robust truck, common lighting issues for this generation often revolve around electrical quirks and bulb failures, especially with aftermarket modifications.

• Flickering Aftermarket LEDs: This is almost always due to CANBUS incompatibility. The system detects the low power draw and tries to send pulses to check if the bulb is working, resulting in flickering. Load resistors or CANBUS-specific LEDs are the solution.
• "Bulb Out" Warnings: Similar to flickering, if the CANBUS system doesn't see the expected resistance from a bulb (especially after an LED upgrade), it will trigger a dashboard warning.
• Moisture in Taillight Assemblies: While not exclusive to the 2020 model, some owners have reported moisture intrusion into the rear taillight assemblies. This can lead to premature bulb failure or, in severe cases, issues with the internal wiring or LED circuitry (if equipped).
• DRL Malfunctions (Halogen): The DRLs on some halogen-equipped trucks are integrated into the turn signal bulbs, which can lead to accelerated wear due to constant use. If one side fails, it's often prudent to replace both to maintain symmetry and prevent future issues.

If you experience persistent lighting problems, especially after an aftermarket installation, it's best to revert to the factory setup to rule out compatibility issues. If the problem persists, it may indicate a deeper electrical issue.

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