Trailer Lights Come On But Brake and Turn Signals Do Not Work Using 4-Flat with 5-Flat Connector

Question

Question:

I wired a 4-Flat connector to my 2002 Toyota Highlander only to realize the trailer I bought had a 5 flat. I assumed that all functions would work since the trailer had no reverse lights or brakes so I plugged it in and skipped one of the connections. I was wrong... The only thing that happens is that the lights come on. I have no brake lights, no turn signals, nothing. I followed all instructions to a tee, all wires are connected to their proper mate. Im not sure what else to do or what, if anything, Ive done wrong. Is there an extra step with my vehicle that I need to know? Another wire to splice into? Please help if you can so I can begin to legally use my trailer.

asked by: Robbie

0

Expert Reply:

You are correct in assuming that the light functions on the trailer should work when connecting the 4-flat connector from your 2002 Toyota Highlander to the 5-flat connector on your trailer as long as everything is wired correctly.

If you are saying that the trailer lights come on when you plug the trailer connector to the vehicle connector and the brake or turn signals do not work, then it sounds like something is not wired correctly.

I suggest using a circuit tester like part # PTW2993 to test the pins on both connectors for functionality. I have attached a video of my co-worker testing a 4-flat connector on a vehicle for you to check out.

If you do not have the proper signals on each pin on the vehicle connector, then the wiring harness that you installed may be either installed incorrectly, is not the correct wiring harness for your vehicle or the wiring harness may be bad. Your vehicle does require a wiring harness with a converter to combine the brake and turn signals.

For your vehicle, I recommend using either the T-One Vehicle Wiring Harness, # 118413, or the Plug-N-Tow Wiring Harness, # 33425.

If the vehicle side connector seems to be operating okay, then the issue may be on the trailer. I would start by making sure all of the ground connections on the trailer and on the vehicle are clean and corrosion free.

Next, I would test the pins at the trailer connector using an independent power source such as a vehicle battery. If you use a vehicle battery, be sure you ground the negative battery terminal to the trailer frame. You can connect the circuit tester to the positive battery terminal to test the pins on the connector for function.

If you have further questions after testing the the connectors to locate the issue, then let me know so we can take further troubleshooting steps.

expert reply by: John H

0

Answer 1

The Curt hitch part #13076 is a confirmed fit for your 2010 Ford Transit Connect and would be a great option. It has plenty of towing capacity at 3,500 lbs total trailer weight and 350 lbs tongue weight plus the hitch is made in America. Since you…

view full answer...

Answer 2

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…

view full answer...

Answer 3

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…

view full answer...

Answer 4

Yep, so long as your 2024 Subaru Crosstrek Wilderness is not a hybrid both the Curt and etrailer hitches will fit: - Curt Trailer Hitch Receiver #C13382 - etrailer Trailer Hitch Receiver #e98912 The only difference besides price is the finish; the…

view full answer...

Answer 5

Hey Antoine, so the two kits you mentioned are actually really similar and honestly I would go with the part #ETBC7 if I were you. The #ETBC7L is basically the same thing minus a couple wires and breakers so you may as well get the kit that has…

view full answer...

Answer 6

I don't think that your wheel size (or lack thereof) has anything to do with the bearings on your HF trailer drying out as much as it is likely that the seal blew out from overfilling the grease or poor installation. This isn't uncommon when…

view full answer...

Answer 7

The Kenda Loadstar ST175/80D13 Bias Trailer Tire #AM3S120 that you referenced is going to close that trailer frame to tire gap by almost a full inch. This would put the new tire much too close to the frame on your Harbor Freight Trailer. The issue is…

view full answer...

Trailer Lights Come On But Brake and Turn Signals Do Not Work Using 4-Flat with 5-Flat Connector

Products Referenced in This Question

Product Page this Question was Asked From

Featured Help Information

Instructions

Miscellaneous Media

Continue Researching