Buzzing Noise from Vehicle to Vehicle Tail Light Converter Part # C56196

Updated 01/15/2025 | Published 08/11/2018

Question:

I have an Aluma trailer to which I have added STL79RB stop/turn/tail lights, and a STL80RB third brake light. The existing lights on the trailer look exactly like your TLL12RK. The STL79RBs are connected in parallel with the existing lights, and the STL80RB is driven by the red wire out of a Curt C56196. The green and yellow inputs to the Curt are driven by the outputs of a couple Hopkins 48955 diodes which are in turn driven by the green and yellow wires of the trailer. The green and yellow output wires of the Curt are unconnected. Everything works as expected, except: 1. When the brakes are on along with a turn signal, the third brake light flashes. 2. Whenever the third brake light is on, flashing or not, the Curt makes an audible buzzing sound along with it. Input current to the Curt is 70 mA from each diode on the green and the yellow inputs. Questions: 1. Is the third brake light supposed to flash under those conditions? 2. Is the Curt supposed to buzz?

asked by: Alan

Expert Reply:

I spoke to my contact at Curt and they informed me that the reason you are hearing the buzzing noise and the third brake light is flashing when using the Vehicle to Vehicle Tail Light Converter part # C56196 is because the green and yellow output wires need to be connected in order to send the proper resistance through the circuits. The only way to properly install a third brake light on a trailer would be to run a signal wire for the vehicle's third brake light to the trailer's third brake light.

expert reply by: Conner L

Julie R.

7/5/2020

I am having a similar issue. I installed the 56196 per the instructions and the running lights and turn signals work properly, but when the brake is applied the converter makes a buzzing sound. I have checked to make sure the ground is good. Any other thoughts?

Chris R.

7/9/2020

Do you by chance have LED lights on the trailer? If so, they might not be drawing enough power to create proper resistance with the converter. You could add some resistors # P230004A-2 in-line with the turn/brake circuits to hopefully resolve this. Let me know if this isn't the case though.

Julie R.

7/9/2020

@ChrisR they are LEDs And I thought it might be something like that, but wasn’t sure how to solve it.

Chris R.

7/14/2020

@JulieR Got it - try adding those resistors and that should hopefully resolve the issue.

See All (5) Replies to Julie R. ∨

Larry

3/14/2024

I am having the same buzzing issue when I apply the brakes. If everything is working, iIs there any long term problem with letting the CURT device buzz other than possibly letting it annoy you?

Mike L.

3/14/2024

@Larry Are you using a # C56196 converter? If so, make sure it's properly grounded to clean, bare metal. Installing load resistors such as # P230004C-2 on the left and right turn signal circuits is also recommended if the ground checks out okay.

Brian

5/19/2024

@MikeL I have 6ohm 50w resistors connected to each turn signal LED (trailer side output) of a Curt 56196 and I still get buzzing when the brake is applied. I’ve tried adding additional resistors to the brake lights but it still buzzes. The turn signals also flicker when the brake is applied. The vehicle is a 2017 Ford Transit 350HD with a 7 pin trailer plug.

Mike L.

5/21/2024

@Brian The buzz is confirmed to be coming from the converter box of the Curt # C56196?

See All (6) Replies to Larry ∨

Martin S.

1/12/2025

Conner L GM vehicles seem to have something happing once he car is started. On battery alone converter works with out buzzing just fine. Do you have any further information regarding what is causing the brake buzzing issue ? Thanks

Kate F.

1/13/2025

@MartinS Hello Martin. I am sorry to hear that you are experiencing a buzzing noise after the car is started, that would drive me crazy. There could be a couple of different reasons this is happening. -First I would check that you have a good clean ground, find where the ground wire is attached to the metal frame of your car and make sure it's tight and touching clean, bare metal. -Too much voltage could also cause the issue. When your car is off it is letting off about 12V, after you start the vehicle your alternator bumps it up to around 14V. You can test this with a multimeter like # PT89ZR. If it’s too high, you might need a small device (voltage regulator) to keep it steady. You can find one at your local auto store. - If the converter is near other wires (like those for the ignition or alternator), it could be picking up extra noise. Try moving it to a different location in your vehicle. After you go through the troubleshooting please let me know how it goes. Fingers crossed you get rid of the buzzing. If you are still experiencing the buzzing please let me know the year, make, and model of the vehicle this is in, and how old is the unit?

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Martin S.

1/13/2025

@KateF thanks! Ground is good My running voltage is ~15 v at ecu. Too much? Might need to check my regulator. Is too much voltage an issue? I would definitely give that a try along with alternator output . Thank you very much

Kate F.

1/14/2025

@MartinS Hello Martin, I reached out to Curt and they informed me that the you cannot use this in your truck to convert your wiring to a 3 wire system, it is only intended for RVs. I have heard of people using this converter in their vehicles with zero issues, and he did not elaborate on why. I still think that a voltage regulator would do the trick, but since Curt is saying you can't use this in your truck, I can't go against what they say. What is the year, make, and model of your truck, and what are you towing? I am going to explore other options once I get that information. I am very sorry for the confusion.