2018 Ram ProMaster Fuse Box Diagram & Amp Ratings

As an ASE-certified master technician, I know firsthand how frustrating electrical gremlins can be, especially on a workhorse like the 2018 Ram ProMaster. Whether your radio just died, the 12V cargo outlet stopped working, or your blower motor quit on a hot day, checking the fuses is always step one.

Below is a comprehensive guide to the fuse box locations, diagrams, and amperage ratings for the 2018 Ram ProMaster to help you get your van back to work.

Quick Answer: Fuse Box Locations on the 2018 Ram ProMaster

The 2018 Ram ProMaster features two primary fuse boxes (often called Power Distribution Centers), along with an optional auxiliary fuse panel depending on upfitter packages.

1. Under-Hood Fuse Box (Engine Compartment): Located on the passenger side of the engine compartment. You will need to remove the protective plastic cover to access the fuses and relays.
2. Dashboard Fuse Box (Passenger Compartment): Located on the driver's side of the dashboard, to the left of the steering column behind a removable plastic trim panel fastened with two screws.
3. Right B-Pillar / Passenger Seat Base (Auxiliary): Many ProMasters ordered with upfitter prep packages have an auxiliary fuse block located at the base of the passenger seat or the right side B-pillar for aftermarket add-ons.

Note: Fuse assignments can vary slightly based on the exact trim, wheelbase, and upfitter packages (e.g., Cargo Van vs. Chassis Cab). Always verify with the printed legend on the inside of your specific fuse box lid.

Under-Hood Fuse Box (Engine Compartment)

The under-hood Power Distribution Center manages high-draw components like the ABS, cooling fans, engine control module (ECM), and headlights. It also houses several essential relays.

Relay Locations: The under-hood box also contains relays for the Starter Motor, A/C Clutch, Fuel Pump, Radiator Cooling Fans, and Horn. Relays are typically designated by "T" numbers (e.g., T02, T05) on the lid diagram.

Dashboard Fuse Box (Passenger Compartment)

This fuse box primarily handles interior electronics, lighting, the infotainment system, and cabin-specific modules.

How to Test a Fuse

Before you start replacing expensive components like blower motors or fuel pumps, check the fuse. Here is the ASE-certified way to do it right:

1. Visual Inspection: Pull the suspected fuse using fuse pullers or needle-nose pliers. Look at the U-shaped wire inside the plastic casing. If it's broken, melted, or blackened, the fuse is blown and must be replaced.
2. Use a Test Light: Ground the clamp of a 12V test light to a bare metal chassis point. With the ignition on, probe the two small metal test points exposed on the top of the fuse. If the test light illuminates on one side but not the other, the fuse is blown.
3. Use a Multimeter: Set your digital multimeter to the continuity setting (the one that beeps). Touch a probe to each test point on the top of the fuse. A continuous beep means the fuse is good. No beep means it has failed.

Safety Note: Never replace a blown fuse with one of a higher amperage rating. Doing so bypasses the safety limits of the circuit and can easily cause melted wires, damaged modules, or a vehicle fire.

Common Blown Fuses on the 2018 Ram ProMaster

Given the ProMaster's heavy use as a commercial and delivery vehicle, certain electrical circuits are pushed harder than others. If you are experiencing issues, check these first:

• Cigar Lighter / 12V Outlets (Under-hood F15/F16 or Dash F44): Delivery drivers frequently plug in dash cams, GPS units, phone chargers, and inverters. Overloading these outlets is the #1 cause of blown fuses in the ProMaster. Check the accessory plug for shorts before replacing the fuse.
• Blower Motor (Under-hood F08): If your A/C or heater suddenly stops blowing air, check F08. If this fuse keeps blowing, you likely have a failing blower motor drawing too much amperage, or a heavily clogged cabin air filter restricting airflow and overworking the motor.
• Radio / Infotainment (Dash F36): If the Uconnect screen goes black, F36 is the culprit. Sometimes a simple pull and reinsertion of this fuse will act as a hard reset for a glitchy radio module.
• Power Door Locks (Dash F38): Cargo vans see a lot of door cycling. If the central locking stops working, verify F38. Also, inspect the wiring harness in the door jamb for broken wires, which is a common cause of short-to-ground issues in these vans.

Electrical diagnostics can get complicated quickly. If you are dealing with a fuse that blows repeatedly the moment you replace it, you have an active short circuit that requires professional tracing.

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