How to Test a 4-Way Trailer Wiring Harness Plug

Question

Question:

I installed a 4 way connector to a 4 way-7way adaptor on my 2000 Mercury Mountianeer. When testing the connector, the test light flashed for the left and right turn signals, but when I ed the tester probe into the 3rd female plug.and applied the brakes, the test light does not go on. Am I doing it correctly ? I assume this is for the brakes. Can you provide some guidance.

asked by: Trubee K

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Expert Reply:

You are testing correctly for the left and right turn signals, but the 3rd female plug you are testing is the taillight circuit. If you turn on the running lights you should get 12 volt power at the connection that the brown wire runs into.

To test the brake lights at the trailer connector you need to apply the brakes and test the connectors that the green and yellow wires go into. These are the same connections that you tested for the turn signals.

Trailer wiring combines the left turn/brake and right turn/brake signal for proper operation of the trailer lights. I have included a video on trailer connector testing for you to review.

The correct wiring for the 2000 Mercury Mountaineer is the T-One wiring harness, # 118345.

expert reply by: Robert G

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Answer 1

The trailer hitch options for a 2021 Hyundai Sonata do require removal of the heat shield. I recommend the Draw-Tite Sportframe Trailer Hitch Receiver part #DT74MR which is a class I hitch with 1-1/4" receiver tube opening. The heat shield…

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Answer 2

Actually, removing the heat shield when installing the Draw-Tite # 24965 receiver hitch on your 2016 Hyundai Sonata isn't a problem because the hitch itself provides more heat protection than the flimsy sheet metal that the heat shield is…

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Answer 3

When you test the 4-Way on the Curt T-Connector Wiring Harness, part #56016, at the rear of your vehicle, it should show now power on all 3 pins with the lights off. If you have the vehicle head lights on, you should have around 12 volts at the brown…

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Answer 4

First you will want to use your Test Light #PTW2993 to test for power going into the Curt T-Connector #C56403 on your 2018 Volkswagen Tiguan. This will allow you to determine if the module is somehow getting a signal or if the module itself is…

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Answer 5

Testing lights on your trailer will require a 12V power source so if you are not going to plug in a connector like #H20046 you will need a separate 12V battery. Then use the negative post of the battery to attach your ground wire to and then and use…

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Answer 6

Many times the issue with a dim light on one side or the other is caused by a poor ground connection. You will want to inspect all of the ground locations as well as the ground wires coming from each light. Check for loose connections or pinched or…

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Answer 7

I suppose it is possible to wire the Curt T-Connector Vehicle Wiring Harness part #C56403 to a lawn mower battery in the trunk area of your vehicle so long as it is 12 volt but I don't really think that is the best way to install the above. The…

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Answer 8

Thank you for your recent purchase of a Curt trailer wiring harness #C56165 and 4 Pole to 7 Pole and 4 Pole Adapter #C57674. LEDs take very little power to illuminate. Some wiring harnesses can pass a tiny amount of power at all times - even when the…

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Answer 9

I would begin by testing the trailer connector on the vehicle to rule that out. Turn the headlights on, and use a circuit tester like part #40376 to test the socket on the connector fed by the brown wire. If you are not getting a signal on this pin,…

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Answer 10

In my experience I have found the T-One Vehicle Wiring Harness #118811 to be the better 4-way wiring for your 2022 Volkswagen Tiguan. The internal components in the powered converter do not go out as often as those in the Curt T-Connector #C56403.

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Answer 11

It isn't the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector #118811 being bad (if that's what you were referencing by "the connector itself"); if that was the case nothing at all would be working as it's the…

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Answer 12

If you are wanting to use a multimeter to test the 12 volt system on your vehicle when you are installing the Curt T-Connector Wiring harness, part #C56165, you would set the multimeter like part #PT89ZR to 20 on the DC side.

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