LED lights not working properly. Pulse Width Modulation?

[TRAILN]

Hi,

I recently upgraded my trailer lights to LED lights. After doing so and checking everything, the lights did not work properly. I found out my new Ford does not work with the conventional 12v system. It uses Pulse Width Modulation (PWM) instead. LED lights and PWM do not seem to work well together.

My car dealership has a TSB on this issue and basically they install a towing module and bypass the (BCM) body control module. By bypassing the BCM, you lose some hi-tech features; one of them is trailer sway control. I don't want to bypass the BCM.

My question is, can I add a load resistor in-line with the trailer wiring? A load to simulate the incandescent bulbs.
Has anyone had experience with such a modification?

 

[TRAILN]

Re: LED lights not working properly. Pulse Width Modulation?

Here is a sample of the resistor

 

[Bondo]

Re: LED lights not working properly. Pulse Width Modulation?

Hi,

I recently upgraded my trailer lights to LED lights. After doing so and checking everything, the lights did not work properly. I found out my new Ford does not work with the conventional 12v system. It uses Pulse Width Modulation (PWM) instead. LED lights and PWM do not seem to work well together.

My car dealership has a TSB on this issue and basically they install a towing module and bypass the (BCM) body control module. By bypassing the BCM, you lose some hi-tech features; one of them is trailer sway control. I don't want to bypass the BCM.

My question is, can I add a load resistor in-line with the trailer wiring? A load to simulate the incandescent bulbs.
Has anyone had experience with such a modification?

Ayuh,.... What, Exactly are they doin' wrong,..??

Is this a Brand New Ford,..?? if not, what vintage,..??

 

[gm280]

Re: LED lights not working properly. Pulse Width Modulation?

I have to admit I have no idea what you're talking about with a PWM circuit used for your trailer light circuit. I fully understand what a PWM circuit is and is capable of doing, but unless the manufactures have starter something new, I have no idea what your setup or your problem... Older and dumber these days...

 

[tpenfield]

Re: LED lights not working properly. Pulse Width Modulation?

Wow . . . I have not heard the term PWM in many years . . . when it was used for digital/analog conversion, etc.

Anyway, there is some info on etrailer.com regarding trailer lights with cars that are using PWM in their electrical system. It sounds like there is some sort of a converter that you need to use to get more conventional voltage to the trailer portion of the system.

I hope that helps and let us know how it gets resolved, since others will probably have similar issues with the newer cars and their fancy electrical systems.

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

If your Ford truly has a PWM system, a load resistor won't work. You would need one of the adapter modules that convert to a normal system.

Did your Ford have the trailering option on it? If it did, I would be very surprised you don't already have the correct wiring.

 

[gm280]

Re: LED lights not working properly. Pulse Width Modulation?

PWM (Pulse Width Modulation) is used to pulse a circuit so the average voltage is around 12-13 volts (I'm guessing here at their voltage in this case). Why they are using such a circuit for trailer lights when the actual battery voltage is already that voltage is beyond me. However, if your lights are dim or blinking very fast because of the actual pulse rate, you could install a capacitor to filter/smooth out those issues. The current on any PWM circuit is the capability of the supply current at any given time. That was the primary issue for using such a circuit in the first place. The current would not be reduced but the voltage would be switched on and off so fast in relationship to each state that the average would equal whatever voltage was needed. The voltage is usually higher and therefore that PWM to supply an average. Don't know what the NEW vehicles are doing these days or why!

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

PWM is used for vehicle lights to allow one wire and one bulb to do both the brake and the running lights. They just change the duty cycle for each function.

The PWM is used for dimming the light during running light mode.

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

2 Questions for the OP

1) Does your vehicle have a trailer package?
2) If it doesn't, how did you get your regular lights to work without a trailering adapter already since your vehicle likely has separate brake and turn wires?

 

[TRAILN]

Re: LED lights not working properly. Pulse Width Modulation?

I'm getting fast blinking on the LED trailer lights. Never had any issues with regular trailer light.
Its a factory installed trailer package on 2013 Escape.
If I combine regular lights with a small LED side marker, everything works fine. I'm guessing because of the higher load.
Even when I plug in my tester I get blinking :grumpy:

 

[oldjeep]

Re: LED lights not working properly. Pulse Width Modulation?

The fast blink usually just indicates a lack of load. Before cobbling in resistors see if you can just replace the flasher relay with one that is meant for trailering.

 

[TRAILN]

Re: LED lights not working properly. Pulse Width Modulation?

The fast blink usually just indicates a lack of load. Before cobbling in resistors see if you can just replace the flasher relay with one that is meant for trailering.

They blink fast just with the taillights on or brake lights on. Not talking about flashing fast with signals on.

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

You do not have a PWM system, at least on the trailer light side. The load resistor would be your fix then.

I did find the TSB

2013 Escape – 2.0L – Equipped With Trailer Tow Package From The Factory – Not Compatible With LED Trailer Lighting – TSB 13-01-05

Some 2013 Escape vehicles equipped with a 2.0L Engine, and equipped with the Trailer Tow Package from the Factory may not be compatible with newer model trailers which have LED lighting. Follow the service procedure steps in this TSB to correct the condition.

If there fix is to bypass the BCM, I would agree that I wouldn't do that. Sounds like they have fixed this problems in newer Escapes.

 

[TRAILN]

Re: LED lights not working properly. Pulse Width Modulation?

You do not have a PWM system, at least on the trailer light side. The load resistor would be your fix then.

I did find the TSB

2013 Escape ? 2.0L ? Equipped With Trailer Tow Package From The Factory ? Not Compatible With LED Trailer Lighting ? TSB 13-01-05

Some 2013 Escape vehicles equipped with a 2.0L Engine, and equipped with the Trailer Tow Package from the Factory may not be compatible with newer model trailers which have LED lighting. Follow the service procedure steps in this TSB to correct the condition.

Multiple sources have been stating PWM. In this one for example, read the third feature down
Wiring by Tow Ready for 2013 Escape - 119190KIT

I did the TSB that Ford recommends. It worked great for the lights but caused other problems for me.

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

Which lights flicker, your running lights or your brake/turn lights?

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

Multiple sources have been stating PWM. In this one for example, read the third feature down
Wiring by Tow Ready for 2013 Escape - 119190KIT

I did the TSB that Ford recommends. It worked great for the lights but caused other problems for me.

That kit is used when your vehicle doesn't come with the trailer package although it might be worth using here.

Like I said before, you don't have PWM on the trailer side. It may be there on the vehicle side of things but since you have seperate wires for the brake and running lights, PWM is not used there.

I did the TSB that Ford recommends. It worked great for the lights but caused other problems for me.

What I am reading on the Escape blogs, you don't want to use Ford's fix.

I think the load resistor or that module are your 2 choices. What a pain Ford is causing here.

 

[TRAILN]

Re: LED lights not working properly. Pulse Width Modulation?

For sure the tail lights. Possibly also the brake lights also. I can't remember exactly

 

[gm280]

Re: LED lights not working properly. Pulse Width Modulation?

Okay, I learned something new today. I do see what they did, but seriously can't understand their reasoning or the fact that addition circuits are used and therefore prone to failure. Such is the design engineers... Thanks Bruseb58 for the reasoning that educated me... I still think it is not a good idea, but that's just me! Seems the manufacturers are making things more complicated them needs to be! So if they do need a "Load" resistor so things work properly again, what have they seriously accomplished?

 

[bruceb58]

Re: LED lights not working properly. Pulse Width Modulation?

For sure the tail lights. Possibly also the brake lights also. I can't remember exactly

Then you would need load resistors on 3 wires. What a pain! I think I would do that if you really love your LED lights.

As far as the size of the load resistor. 7W would probably be all you need. That would mean you would need to draw 7/12 amps which would mean a resistor that was 20 ohms. So, get a 20 ohm 20W resistor for each 3 legs.

 

[oldjeep]

Re: LED lights not working properly. Pulse Width Modulation?

You would think that some enterprising person would start selling a little harness with a 4 pin on each side and resistors in the middle if this is a common problem.