How Does a Brake Controller Know when a Trailer is Connected

Question

Question:

Good morning, question is what signal is the brake controller receiving when trailer plug 7 wire is plugged into the vehicle

asked by: Marv

1

Helpful Expert Reply:

When a trailer with electric brakes is connected to a vehicle that has a brake controller that brake controller is sensing the draw of the brake magnets by sending back a small amount of voltage on the blue wire.

The brake controller also get's signals from the tow vehicle to let it know when you are stepping on the brake pedal. On most vehicles this connection is made either at the brake switch above the brake pedal or through some kind of tow package wiring.

I have included a link to our help article on brake controllers for you. It covers proportional and time delay controllers. If you are in a market for a controller I recommend a time delay such as the P2, # 90885. Proportional controllers activate the trailer brakes in proportion to how much the vehicle is braking using internal sensors. This is the safest way to stop and it reduces wear and tear on the vehicle and trailer.

expert reply by: Michael H

1

Jim W.

3/29/2020

I have a Hopkins Agility Brake Controller about 2 years old. The controller worked up to about a month ago indicating the trailer was connected. The red lamp that indicates this stoped working. The controller has voltage and ground from the battery and receiving voltage from the brake peddle. Blue wire good from the controller to the battery connections that stops a brake away trailer. Would one magnet cause the indicator to disappear or the brakes on the trailer to stop working?

Reply

Chris R.

3/31/2020

A bad brake magnet could be enough for the controller to sense a lost connection, since their draw is what is used to detect this. If you found that the brake magnet is bad, it certainly wouldn't hurt to replace it to see if it resolves the issue since it need to be done, anyway. Also check the power and ground wires coming from each brake assembly to make sure they're still securely attached - these (especially the ground wire) can come loose over time.

Reply

Alice

5/2/2024

I have no brake lights with no trailer connected, how can I fix that

Reply

Answer 1

The towing capacity of a 2018 Chrysler Pacifica is 1,500 lbs if you don't have the factory tow package or 3,600 lbs if you do have the factory tow package. The use of electric trailer brakes is pretty common nowadays and I recommend looking for a…

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Answer 2

The reverse light pin on a traditional 7-way trailer connector, like part #PK11893 or a factory connector if that's what you have on your 2018 Ram, is the center pin. Take a look at the picture I attached that shows all the pin functions. To add…

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Answer 3

I was able to verify that we do have a hub and drum compatible with 13 inch wheels, but the Easy Grease Trailer Hub and Drum Assembly for 2K Axles #AKHD-545-2-EZ-2K is only compatible with 10 inch or 12 inch wheels. Instead, what you will need is one…

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Answer 4

I don't have any way of knowing if the Electric Trailer Brake Kit - 7" - Left and Right Hand Assemblies - 2,000 lbs #AKEBRK-2 will work for a 1996 Coleman/Fleetwood pop-up, but if you aren't sure of the axle weight you can measure the…

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Answer 5

The reason for the price difference is the Dexter Trailer Hub and Drum Assembly #8-271-7UC3-EZ are only compatible with hydraulic brakes, where the #8-257-5UC3 are compatible with electric and hydraulic brakes. Since most people use electric trailer…

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Answer 6

The Scissor Stabilizer Jacks w/ Handle #TJSCHD-24 are typically mounted perpendicular to the beam but you can definitely still mount them inline with the beam. The only problem you might run into is trying to get it mounted to the frame since the…

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Answer 7

Hello Calvin. That is an interesting question. Usually, most folks want to go with larger wheels instead of smaller. The main problem we are going to run in to here, it that the hubs that are made for a 10" wheel will not fit on an axle/spindle…

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Answer 8

Both the Dexter Electric Trailer Brake Kit #23-47-48 and the Electric Trailer Brake Kit #AKEBRK-2 are excellent options to replace the brake assemblies on your 2009 Palomino Pony pop-up camper. A lot of the Dexter Axle kit price comes from the name…

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Answer 9

The recommended hub/drum size for a 13" diameter wheel is one that is for 10" diameter brakes. The wheel will still fit on the hub/drum assuming the bolt pattern matches there is just less surface area on the hub for the wheel. However, you…

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Answer 10

Aftermarket brake controllers send a small amount of voltage along the brake output wire, if a trailer is connected, the magnets in the brake assemblies will create a power draw. This power draw tells the controller that a trailer is connected. The…

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Answer 11

If you are looking for a way to power the trailer brakes you would not run the blue wire of the 7-way to the positive post of your battery. Instead you would run that wire up to the blue wire of a brake controller like the part #90885 that you…

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Answer 12

You can use 14 or 16 gauge wire for your marker and tail lights on your camper. I recommend using the Deka 14 gauge jacket wire #DW04923-1 because it's insulated for abrasion and chemical resistance. Having more marker lights means more draw on…

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How Does a Brake Controller Know when a Trailer is Connected

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