Comparing Optronics # ST40RB and Optronics # STL003RFLB Trailer Lights
Updated 01/23/2019 | Published 01/22/2019 >
Products Featured in This Question
Question:
Hi there, The light Im replacing only has two wires. What is the third white wire for on this? Similar to Item # ST40RB Id like to get the LED instead but just want to make sure Im not missing something. Thank you!
asked by: Samuel B
Expert Reply:
Aside from the Optronics # ST40RB having an incandescent bulb and the Optronics # STL003RFLB being LED the only other big difference is that the first part grounds through the mounting hardware while the LED version grounds through a wire. This is why one unit has 2 wires and the other has 3.
We have 2 pigtail options for the LED verison for you to use. Part # A45PB has the wires coming straight out of the plug while part # A47PB has a right angle for tight spacing where your lights mount.
I have attached some sample installation videos for you to check out.
Product Page this Question was Asked From
ONE LED Trailer Light w/ Flange - Brake, Tail, Turn - Submersible - Round - Red
- Trailer Lights
- Tail Lights
- Brake/Tail/Turn
- Round
- Recessed Mount
- Submersible Lights
- LED Light
- 4-1/4 Inch Diameter
- Red
- Optronics
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Q&A: Tie-Downs for 2026 Ford F-350 Long Bed With Factory Hitch
- Q&A: Will the Replacement Red Lens # A42RB Replace Do Ray SS-105
- Q&A: Adapter Plug For Optronics ONE LED Tail Light
- Q&A: How To Install Break Away For Brake Buddy Braking System
- Q&A: Will GloLight LED Trailer Tail Light Fit Flange
- Q&A: Bolt Recommendations for a Equalizer for 2 inch Slipper Springs
- Q&A: Comparing Lippert Never-Fail Bushings to the Bronze Bushings and Wet Bolt Option for Tandem Axles
- Article: Trailer Wiring Diagrams
- Article: Our Team Picked The Best Camping Gear of the Year - Here Are Their Top Choices
- Article: Trailer Lighting Requirements
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: Troubleshooting Brake Controller Installations
- Article: 5 Reasons to Convert Your RV Lights to LEDs Today
- Article: How to Tell the Weight Rating of a Trailer Axle



