Replacing 4 Pin Plug On Trailer - Old Harness Has 3 White Wires 3 Brown Wires 1 Yellow 1 Green

Updated 10/12/2026 | Published 10/10/2026

Products Featured in This Question

TowSmart 4-Way Flat Trailer Connector w/ Wire Tester - Trailer End - 24"

(3)

$10.06

35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

(872)

$28.77

Deka Heat Shrink Butt Connector - 12-10 Gauge - Nylon Insulation - Yellow - Qty 5

(1186)

$8.58

Question:

I need to replace my 4 prong connector on my trailer but when I spliced the harness it had 3 white wires,3 brown wires, 1 yellow wire and 1 green wire and I can’t find a harness to repair this type of fix. What do I need to do?

asked by: Randy L

Expert Reply:

Hey Randy,

Good news! You can use a standard 4-way trailer connector like the TowSmart 4-Way Flat Trailer Connector w/ Wire Tester - Trailer End - 24" # TS84RR to replace your existing connector. If you want to run new wires all the way down, use 35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground # A35W42B.

It sounds like your trailer has multiple ground and running light wires that are routed directly to the connector rather than combined farther back.

You'll just need to connect the wires as follows:

All 3 white wires to the new white ground wire.

All 3 brown wires to the new brown running light wire.

Yellow to yellow for the left turn signal and brake light.

Green to green for the right turn signal and brake light.

I'd recommend verifying the wire functions first, then using appropriately sized heat-shrink butt connectors to protect the connections from moisture. Usually # DW05745-5 is a good heat shrink butt connector to use.

You won't need a special 8-wire harness for this setup as this trailer was just wired all at the connector instead of splitting the light circuits later down the trailer harness; no big deal!

Let me know if you have any other questions!