Ram ProMaster Tail Light Bulb Size

Additional Notes

• The two bulb types specified for the Ram ProMaster tail light are the 7440 and the 7443, both of which are T20 wedge-base bulbs operating at 12 volts and recognized under ANSI standards in the US and Canada.
• The primary technical distinction between the two types is filament count. The 7440 carries a single filament rated at 21W, while the 7443 carries dual filaments rated at 21W and 5W respectively.
• The dual-filament design of the 7443 allows it to serve two lighting functions within a single bulb, with the higher-wattage filament typically handling the brake or turn signal function and the lower-wattage filament handling a secondary function such as running or parking light.
• The 7440 single-filament bulb, by contrast, is limited to one lighting function per socket, which reflects a different tail light assembly design in the 2023-2024 model years.
• The Ram ProMaster used the 7443 across the 2014-2022 model years, making it the longer-running specification across the vehicle's production history covered in these data.
• The 7440 is specified for the 2023-2024 model years, representing a change from the dual-filament 7443 used in prior years.
• Although the 7440 and 7443 share the same T20 wedge base and physical housing form, they are not interchangeable. Installing a 7440 in a socket designed for a 7443 would leave one lighting circuit without a functioning filament.
• The reverse substitution, placing a 7443 into a 7440 socket, may fit physically but introduces an unused filament and potential compatibility issues depending on the vehicle's wiring configuration.