Troubleshooting Trailer Brake Lights Not Working With 2021 Ram ProMaster 2500

Question

Question:

Hello, I purchased and installed the trailer kit ITEM # 118618, pretty easy install. ram promaster van 2500, 2021 I then added the 4 to 7 adapter. ITEM # 30717 I hooked up the trailer and nothing. My friend hooks it up to his truck and it works. So I tested the 4 pin, and get good ground, right, and left, but no brake lights. Turn signals also work. On the 7 pin, i get a good ground, rgith and left lights and turn signals, but again no brake lights. Also I loose the right and left lights with the brakes are applies. I also connecting the black 12v power from the 7 pin, and no imporvement to a fused line. Please help, why wont it work?

asked by: Randall M

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Expert Reply:

To begin troubleshooting this problem I recommend checking the connections on your T-One Vehicle Wiring Harness # 118618. Often when one function is not working it is due to a set of connectors not seated together properly. Try disconnecting and reconnecting the harness to ensure the connectors are seated together properly.

While you are checking the connection it might be a good idea to give the wires a quick inspection. Although it is a new wiring harness, it is possible a wire got pinched or nicked resulting in a short.

Another thing you can try is moving the ground to a different location since a bad ground can cause strange issues like this. Realistically the brake lights should work since the turn signals work and they run off of the same wire as the brake lights.

I have attached a helpful article on troubleshooting 4-way wiring for your reference. I lists troubleshooting steps in detail for a variety of different problems. If this does not get your brake lights working please reach out and I will help you troubleshoot further.

expert reply by: Robin H

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Answer 1

It sounds like you either have bad grounds for the brake assemblies or you are using too small of gauge for the brake assemblies themselves. The brake output circuit should be 10 gauge wire like the part #10-1-1 which is sold by the foot. Make sure…

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Answer 2

It sounds like the left side may have a bad ground in the system or a loose ground. I would check over the complete wiring system and make sure all grounds have a good metal contact and no rust. Also check the wires to make sure the protective…

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Answer 3

The manufacturers for the majority of trailer tires do recommend that they always be inflated to the listed maximum psi, regardless of how the trailer is actually loaded. This just ensures that the listed weight capacity is maintained and that they…

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Answer 4

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Answer 5

Goodyear makes really good tires. However we have been really impressed with this newer brand we've been carrying, called Taskmaster. I have attached a link to all of the Taskmaster tires we carry. If you can let me know what size tires are on…

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Answer 6

Currently Goodyear is one of the few trailer tire manufacturer that makes tires in the USA and the only one that we carry. Unfortunately they do not currently offer a tire size of 235/80-16.

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Answer 7

Since you are wanting to exceed the speed rating of most trailer tires (65 mph) I would highly recommend you go with the part #TTWPRG235R16. The 81 mph speed rating will help quite a bit. You currently are exceeding the speed rating of your tires in…

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Answer 8

There are a few things you can do to test out the OEM brake controller in your 2019 Ram pickup. First of all most OEM brake controllers are proportional like the Prodigy P3 #90195. With this being the case it won't apply the brakes on your…

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Answer 9

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 10

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 11

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 12

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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