Troubleshooting Trailer Lights not Working After Harness Install

Question

Question:

Installed trailer wiring harness and the lights on trailer still don't work. Any suggestions? Thanks.

asked by: Bob

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Expert Reply:

There are a number of steps for you to take to figure out exactly why the lights on your trailer are not working. You did not specify the harness you used, but for a 2007 Honda Odyssey, there are three fits, the T-One # 118438, Curt # C56161, and Hopkins # HM11143115.

To start, we'll isolate the problem to either the trailer or vehicle. You can do this by using a circuit tester such as # PTW2993 to check the functions of the 4-way plug while somebody else engages them (brake, turn signal, taillights). If there is an issue, check for a blown fuse. However, if all the functions are right, this will tell us the wiring harness is fine and the problem is on the trailer side.

You will need to check to ensure the wires are connected in the right locations, and that the ground wire is attached to the trailer frame in a clean surface free of any paint, dirt or rust. I have linked an article called "Troubleshooting 4 and 5-Way Wiring Installations" you will want to follow, as well as an article on trailer wiring which you will want to look over.

expert reply by: Kyle S

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Answer 1

Fishwiring is when you run a bolt leader, which is a long wire that on one end you can thread a bolt (it looks like spring), through the hole the bolt needs to go in, and out through a larger access hole. You then put on a spacer block or washer,…

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Answer 2

Through your testing you have proven that the issue is on the vehicle side and not the trailer side. Your four pole connector has a wires colored green for right turn signal and brake lights, yellow for left turn signal and brake, white is ground,…

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Answer 3

There are a couple of things to check with the installation of Curt trailer wiring harness #C56378 on your 2016 Honda Odyssey. First, make sure the fuse is installed in the red power wire. If it is installed make sure that the fuse is good and…

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Answer 4

It's possible the converter box has an internal short and that's why the running light circuit isn't working. What you can do first though is try unplugging and replugging in the connections of the harness as sometimes a contact just…

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Answer 5

Sounds like the trailer wiring issue you have for your 2014 Honda Odyssey is related to the tow package wiring setup of the vehicle. What I would recommend first is to check under the hood of your vehicle for the trailer running light circuit fuse…

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Answer 6

Converter boxes like what is on the Tow Ready Wiring Harness #118349 can short out. Actually if there's a short on the trailer wiring they tend to short out pretty frequently. If you tested the input side of the box and the voltage is there when…

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Answer 7

Sounds like you are looking at position #5 on the drivers side fuse box of your 2005 Honda Odyssey Touring. When installing the Tow Ready T-One Wiring Harness, part #118438, on your Odyssey you will want to locate the fuse compartment on the…

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Answer 8

You will need to attach and secure all 6 bolts holding the Curt Trailer Hitch Receiver part #13322 to your 2007 GMC Sierra Classic. Not attaching all 6 bolts would void the warranty of the hitch and likely affect its capacities/performance. I…

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Answer 9

Apparently, on the 2014 Chrysler Town and Country, on the passenger side frame rail there is a bolt that is holding on the bumper and it should not or cannot be removed. Otherwise there would likely be 6 bolts instead of 5 holding on Curt trailer…

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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

If the trailer wheels scrubbed (dragged and scrapped the ground instead of rolling) when jack knifed then it could have thrown something out of alignment or damaged something. First, inspect the suspension. Look for any elongated holes where…

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