Determining Circuit Functions of Harness that Ran to Ford F-350 7-Way Connector
Updated 11/03/2025 | Published 01/29/2025
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Question:
Jus received this item from your store Curt Universal Wiring Harness for Vehicle-End Trailer Connectors and was wondering if you have any resources or wiring diagram for a 2008 Ford f350 6.4 diesel XL pickup with a 7 round pins plug. I already cut off that plug but the wire colors dont match up with item 56229 USCAR adapter. Any resources to get those wires identified? Thx Carl
asked by: Carl W
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Expert Reply:
Hey Carl, since the wires were already cut your best option would be to use a circuit tester like the part # PTW2993 to test all of the wires for voltage when you apply the various turn signal circuits. So for example put on the left blinker and test all of the wires till you find one that has flashing voltage and label that as left turn/stop circuit. The # C56229 circuit that matches that would be the color yellow. Here's the rest of the wire colors on the harness explained:
Green: right turn signal
Yellow: left turn signal
White: ground
Brown: tail lights and side marker lights
Blue: electric brake
Black: auxiliary power
Purple: backup/reverse lights
Let me know if you get stuck during this process!
Product Page this Question was Asked From
Curt Universal Wiring Harness for Vehicle-End Trailer Connectors
- Accessories and Parts
- Trailer Wiring
- Vehicle Wiring Harness
- Universal
- 7 Blade
- CURT
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Jameson C.
11/3/2025
Hey Carl, how did things go using the circuit tester to match the wires on your F-350 with the Curt harness? Were you able to get all the circuits labeled correctly? Your results could really help others tackling the same wiring job.