2020 Ram ProMaster Bulb Size Guide: Headlight, Tail, Fog

As an ASE-certified master technician, I frequently work on commercial fleets and camper van conversions, making the 2020 Ram ProMaster a regular visitor in my bay. Built on the Fiat Ducato platform, the ProMaster has some specific European-influenced design traits that apply to its electrical and lighting systems. Getting the correct bulb sizes is essential before you start tearing into the front end or rear light assemblies.

Below is your comprehensive guide to the 2020 Ram ProMaster lighting system, from standard replacements to LED upgrades.

Quick reference

Here is a quick reference chart for the 2020 Ram ProMaster bulb sizes. Note that most ProMasters in the US market come standard with halogen housings, though specific trim levels or upfitter packages may feature slight variations.

Note: Always verify your specific housing before purchasing. While H7 is standard for both low and high beams on the standard reflector housings, DRL and turn signal sizes can occasionally differ based on whether you have the basic or premium headlight packages.

LED vs halogen upgrade considerations

Upgrading your 2020 Ram ProMaster to LEDs is incredibly popular, especially for camper van builders and delivery drivers needing better nighttime visibility. However, the ProMaster’s European electrical architecture (CANBUS) is notoriously picky.

• CANBUS Errors: The vehicle's computer constantly monitors electrical resistance to detect burnt-out bulbs. Because LEDs draw significantly less power than halogens, the system will often throw a "bulb out" warning on the dash or cut power to the light entirely.
• Anti-Flicker Adapters: To run H7 LED low beams successfully, you will almost certainly need CANBUS decoders or load resistors installed inline with the bulbs to mimic the halogen power draw and prevent flickering.
• Retainer Clips: The H7 bulbs in the ProMaster use a specific retaining clip. Many aftermarket LED bulbs are too bulky to fit the factory clip, meaning you may need to purchase aftermarket ProMaster-specific LED retainer adapters to secure the bulb in the housing.

How to replace each bulb

Here are a few quick technician tips to help you replace your bulbs without breaking plastic tabs:

• Headlights (Low/High Beam): Unlike standard sedans where you reach behind the housing, the ProMaster often requires partial removal of the front fascia or grille trim to fully unbolt and pull the headlight assembly forward. Once the assembly is out, the H7 bulbs are easily accessed via the rear dust covers.
• Fog Lights: These can be accessed from underneath the front bumper. Removing a few T25 Torx screws on the lower splash shield will give you enough room to reach up, twist the H11 bulb counterclockwise, and disconnect the harness.
• Tail Lights (Brake/Turn/Reverse): The rear housings are much easier. Open the rear doors, remove the retaining screws on the inboard side of the taillight assembly, and carefully pop the housing off its outer alignment pins. The bulbs sit on a single circuit board tray that unclips from the main lens.
• License Plate / Side Markers: Use a plastic non-marring trim tool to gently pry the housings out of the sheet metal. The 194 wedge bulbs simply pull straight out.

Common lighting issues for this generation

The Ram ProMaster is a tough workhorse, but its electrical system is prone to a few specific quirks:

1. Tail Light Ground Faults: The rear taillight circuit board is known for weak ground connections. If you notice your brake lights dimming when your turn signal flashes, or you're getting random dash errors despite the bulbs being good, the ground wire in the main harness connector is likely overheating and melting. Hardwiring a secondary ground to the chassis usually fixes this.
2. Hyperflashing Turn Signals: If you upgrade the front or rear turn signals to LED without adding a load resistor, the flasher relay will pulse rapidly.
3. Water Intrusion: High-mileage vans often suffer from cracked roof marker light seals, leading to water dripping into the cab and occasionally shorting out the interior dome lights. Check the gaskets on your upper clearance lights annually.

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