No Trailer Brake or Turn Signals When Connected to 2012 Ford F-250 With Factory Tow Package

Question

Question:

when I hook up the trailer I have running lights only, no brakes or turn signals. the trailer is newly wired and was working fine , until .........

asked by: Mike

1

Helpful Expert Reply:

Troubleshooting your brake and turn signal problem is easiest when you disconnect the trailer and test the truck and trailer individually.

First, at the truck check all fuses and relays related to trailer/towing in the power distribution box. If these are all okay, then next apply a tester like # PTW2993 to your 7-way connector. You will want to test one circuit at a time while a helper activates each function on the vehicle. The linked photo shows you the function assignments on a typical 7-way. Stop and turn signals are carried on two wires, yellow for the left turn and stop and green for the right turn and stop. Apply the grounded tester's probe to the pin at the 9-o-clock position while the brake and then left turn signal are activated. With the brake pedal pressed there should be a steady signal on the pin; with the left turn signal engaged there should be an on-and-off blinking signal. Repeat the test for the 3-o-clock pin with the brake and right turn signal. If the results are correct, then you can move on to the trailer. If not, then you may need to clean your 7-way if it is corroded or replace it with part # HM40975.

You can test the trailer lights quite easily by directly connecting a 12V power source (such as a spare battery or the truck's battery) to the pins on the 7-way plug to see if the trailer lights operate as they should. Apply the negative wire to the ground pin (the 5-o-clock position as you look at the contacts on the trailer plug) and then apply the hot wire to the 3- and then the 9-o-clock pins. This will tell you if the trailer wiring is correct and functioning correctly.

If the trailer lights do not work then you will need to trace the wires for these two circuits from the connector, along the trailer frame, all the way to the individual lights, looking for pinch points, damaged insulation or loose connections. The linked article includes additional troubleshooting help.

expert reply by: Adam R

1

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Answer 1

You will first want to check the fuses on your tow vehicle. Some vehicles could have fuses for operating the turn signals and brake lights of a towing package. You will want to check if they are installed and working properly. The next thing is to…

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Answer 2

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 3

In order to actuate the trailer brakes, you'd need a brake controller installed in the vehicle and a 6 or 7-way trailer connector. A 4 pole flat wiring harness like the #18002 you'd looked at carries 4 circuits- right turn/brake lamp, left…

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Answer 4

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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Answer 5

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 6

The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity. For a ST175/80D13 like…

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Answer 7

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 8

From what I could find it looks like your 122R (red) and 122Y (amber) lights measure 3.75" x 1.70" x .81". We don't have any replacement lense directly for the GLO-BRITE lights but we do have some similar lights that you could use…

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Answer 9

I did some checking and the hub/drum we offer that will work for you is the part #8-430-5UC3. This uses the same bearings as the 8-415 and will be an exact fit aside from the fact this is a non-ABS setup and the 8-415 came in an ABS setup and non-ABS…

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Answer 10

Load range B trailer tires are going to have a lower capacity than C load range tires. Basically that, psi rating, and the ply rating are the only differences. A higher load range tire would last a little longer than lower load ranges of the same…

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Answer 11

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose #8-258-5UC1. If the inner bearings are marked…

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Answer 12

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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