Troubleshooting Trailer Wiring Where No Lights Work

Question

Question:

Hi, I just bought the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector C56327 for our 2024 Ford transit 150. I installed it, the tail lights were working, but when we plugged in the trailer, the trailer lights did not work. We got another harness thinking it was that, but still the same issue. I have it wired to the battery under the driver seat, could that be the reason the lights arent working? Or could it be something else? Thank you

asked by: Matthew F

0

Expert Reply:

Hey Matthew, are you sure the problem isn't the trailer taillights? Do you have a circuit tester that you could test the pins of the 4-way with to see if you can find out if the problem is for sure on the vehicle or trailer side?

expert reply by: Jameson C

0

Matthew F.

9/25/2025

Hi, It is not the trailer. The trailer works with my other trucks. I have bought other harness for our Mavericks and they work fine with this trailer. Not sure what it could be.

Jameson C.

9/29/2025

@MatthewF Is the battery under the seat for sure a 12 volt battery? It should be but I tried to look up that info and wasn't able to verify that.

Matthew F.

9/30/2025

@JamesonC Yes it has the 12v battery under the seat.

Jameson C.

9/30/2025

@MatthewF Do you have a circuit tester like the part # PTW2993 so that you could test for voltage on the input and output side of the converter box?

Answer 1

Howard, I totally get what you’re running into here, and you’re not alone, this is a common headache on newer Mavericks with BLIS. The issue isn’t the light bar itself, it’s that anything plugged into the trailer connector tells the truck a trailer…

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Answer 2

Hello Warran, we sure do! For the 2025 Ford Maverick Hybrid without LED taillights you will need the following: - Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector #C29PQ What are you planning to tow first with your Maverick?…

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Answer 3

The 12V power lead for any wiring kit, including the Curt T-Connector #C59DR for your 2022 Ford Maverick, will potentially need more power than a 12V socket will be able to provide. The whole point of having a separate power and module in a kit like…

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Answer 4

Hey Bill, thanks for reaching out! Yes, you can still install the Curt T-Connector Vehicle Wiring Harness #C59DR even if your 2024 Ford Maverick has the factory tow package. This wiring tees in behind the tail lights and then pulls power straight…

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Answer 5

We get this question a lot but unfortunately our answer is always the same, you must run a wire all the way up to the battery when installing a trailer wiring harness like the Curt T-Connector Vehicle Wiring Harness part #C59DR. The reason for this…

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Answer 6

Newer vehicles have much more delicate taillight circuits than older vehicles which is why they can't handle powering additional trailer taillight circuits. This is why the harnesses that fit your Maverick like the #119147KIT require running the…

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Answer 7

You need to route the 12V power wire from the Curt T-Connector Vehicle Wiring Harness with #C59DR up to the battery under the hood of your 2022 Ford Maverick, which we demonstrate how to do in the linked installation video. I also recommend picking…

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Answer 8

The Curt trailer wiring harness part #C59DR that you referenced is rated for up to 5 amps per stop/turn circuit and 7.5 amps for the running light circuit. While this is less than 20 amps we still have to recommend you run the power wire for this kit…

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Answer 9

This is a problem we normally see with German vehicles when they try to tow a trailer with LED lights. The issue is that the lower amperage draw of the LED lights is just enough to confuse the vehicle that it is drawing too much and because of that…

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Answer 10

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 11

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 12

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Troubleshooting Trailer Wiring Where No Lights Work

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