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Troubleshooting No Running Lights on 7-Way Square Plug for 2000 Ford F-350 Super Duty


Ive got the same problem but on a 2000 F350. All fuses good under the hood #4, #8, and #28. So with all of that done I went to the trailer plug on the truck still no trailer running lights. Under the hood under the break booster on fender well are 4 plugs 2 to transmission and the other 2 are for the Turn, Break, Stop Lamps and Ect.... on the truck and the other is for the Turn, Break, Stop Lamps and Ect.... for when the trailer is plugged into the truck providing trailer with lights Ect.... So I unplugged the 4th plug from the left located on fender well below break booster and fuse box. This plug sends power ect to the 7 pin trailer plug on back of truck. I then used an Ohm meter and a very long wire to test each of the pins of the 7 pin plug and the male plug under the hood which all tested good. So now I know which pin in the male plug operates the trailer running lights. The test on the pin which operates the trailer running lights in Female plug has no power whatsoever going to the trailer running lights when truck park lights are on with the key on or off. So now where and what do i trouble shoot. BTW I replaced the hard to reach Blinker Relay under the dash to the right of the steering column. Need help Thanks


Expert Reply:

Thank you for all of the details! Troubleshooting trailer lights can be frustrating and it sounds like you've already put in a lot of effort.

If the connector sending the signals on the truck side has all of the functions active and operating properly then you can simply replace the factory 7-Way connector on your 2000 Ford F-350 Super Duty with either the Tow Ready # 118243 which has a shorter lead or the Draw-Tite # 20031 which has a longer lead.

If the problem is that the square connector for the trailer functions on your F-350 ISN'T sending power then there are 2 possible solutions; you can either cut off the square connector that goes to your 7-Way and splice in those wires to the OEM wires on your truck using butt connectors # DW05744-10 and # DW05745-5 OR you can potentially tee in the Hopkins 7-Way # HM40157 to that other square connector that carries the same functions. Just note that this will cause extra draw on those circuits.

Aside from that you'd need to take your pickup to a shop or dealer and have them run replacement wiring for the factory side of the connection between the fuse box and that square plug.

Square Plug Connector for Trailer 7-Way on 2000 Ford F-350 Super Duty
Square Plug Connector for Trailer 7-Way on 2000 Ford F-350 Super Duty
(click to enlarge)
expert reply by:
Jon G

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