How to Connect the # STL42RB Tail Lights to a 1958 Trailer with 2 Wire Lighting System

Published 11/30/2010

Products Featured in This Question

Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diodes - Round - Red Lens

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$18.66

3-Wire Pigtail for Optronics Trailer Lights - 3-Prong PL-3 Plug - 10" Lead

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Right Angle 3-Wire Pigtail for Optronics Trailer Lights - 3-Prong PL-3 Plug - 10" Lead

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Optronics LED Backup Light for Transit Vehicles - Submersible - 42 Diodes - Round - Clear Lens - 12V

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Optronics Transit LED Light - Parking and Turn Signal - Submersible - Surface Mount - Round - Amber

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Optronics LED Transit Tail Light - Stop, Tail, Turn - Submersible - 31 Diodes - Red Lens

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Question:

Your Stl42RB lights say they connect with a three prong plug. Our trailer is a 1958 and only has two wires. Can I cut the plug off and attach ground wire to tailer body? Plus we really like the round lights but we would prefer a little larger one than four inches, do you have anything with three functions that is larger. Thank you for any info you have.,Thank you for answering my question, your company is very helpful. My question to you is will the 7 inch round light you recommended work as a turn signal also obviously we need to conform with laws that require turn signals.

asked by: Ron S

Expert Reply:

The 4 inch Round Sealed LED Stop, Turn or Tail Light, item # STL42RB, uses a 3 wire pig tail, item # A47PB or # A45PB, to connect to your existing trailer wiring. The plug on the pigtail plugs into the back of the tail light and is then hard wired to your trailer wiring.

It sounds as if your original tail lights were grounded to the trailer frame through their mounting studs, so a third wire was not needed.

When connecting the 3 wires from the 3 wire pig tail, you will ground the white wire to the trailer frame. The white wire comes with a ring terminal attached to the end for this purpose, but if the wire is too short to reach an appropriate spot on the trailer frame, it can be extended. You will then attach the red wire to the turn/stop light circuit and the black wire to the tail light circuit.

We do have a surface mount light that is 7 inches in diameter. This light is not a flush mount light, like the light you selected. The 7 inch Round Transit LED Stop and Tail Light, item # STL90RB, may be what you are looking for. This light comes with the 3 wires for connection in the same way as the # STL42RB lights mentioned above.

The 7 inch round light is also available in an Amber turn signal light, item # STL90AB, and as a backup light, item # BUL90CB.

expert reply by: Robert G

Ron S.

11/30/2010

Bob G.

11/30/2010

Yes, the lighting on your trailer is a two wire system with the brake and turn signals on the same circuit, so when the brake is applied and the turn signal is turned on the appropriate side will blink with the # STL90RB, 7 inch Round Transit LED Stop and Tail Light. When the tail lights are on the light will have a dimmer appearance and brighten when the brakes are depressed. When a turn signal is activated without the brake depressed the light will blink brightly with or without the tail light circuit activated. This is true for both the red, # STL90RB and the amber # STL90AB lights. The Amber light is designed for use in a 3 wire system where the turn signal is separate from the brake signal. The BUL90CB light is only designed as a backup light and only has two wires, ground and power.