Trailer Lights Gurus--Got a Question.

[npalen]

Can you elaborate?

Yes, please elaborate.

 

[IndyJay]

Not sure if this is the case here, but unlike traditional incandescent lamps, LED lights are polarity specific. Any chance of polarity being crossed somewhere?

 

[npalen]

Not sure if this is the case here, but unlike traditional incandescent lamps, LED lights are polarity specific. Any chance of polarity being crossed somewhere?

I did verify that the white wire at the connector is negative and the others are positive when voltage is present.

 

[IndyJay]

I did verify that the white wire at the connector is negative and the others are positive when voltage is present.

Guess that would be both at the truck connector and at the individual lamp connector.
To quote Wiston Churchill, this is "a riddle, wrapped in a mystery, inside an enigma"...

 

[npalen]

Another concern is there are two other colored wires in addition to the white wire on each light. The diagram below shows the two colored wires attached to seperate leads. My trailer just has the white wire on each side plus a colored wire so I spliced the two colored wires of the light together with the colored trailer wire at each light location. Maybe this is incorrect but not sure how else one would do it.

 

[Doughknob]

Edit: Something I don't understand is how the taillights get the different signals for running light, blinking etc thru the same wire. It seems that all the voltage going thru the trailer connector is 12VDC even when blinking for the turn signal the DMM appears to go from 0 to 12 even though rapidly.

Not same wire. Brown is running lights on 1 filament in the bulb. Green or yellow is the blink signal through 2nd filament in the bulb.

 

[herm0016]

oh....

you should have 3 wires, a ground, a stop lamp and a signal lamp( constant on for brakes, and on/off flashing for turn signal. connecting the brake and signal lamp wires would probably make things act strangely with the led drivers in the tail lights.

same as you have a left signal, right signal, and running light wire and ground at the plug.

 

[npalen]

Not same wire. Brown is running lights on 1 filament in the bulb. Green or yellow is the blink signal through 2nd filament in the bulb.

There is only one wire besides the ground wire. So the signal for all the functions has to go thru that wire. Right?

Also on LED trailer lights I think it is the number of LED's that are lit to distinguish between the various functions. (dim and bright, blinking etc)

I understand the seperate filaments in incandescent lights but, again, how the signal for seperate filaments is sent thru the one wire. (different voltage?)

 

[Midniteoyl]

You know, guys, the trailer brake actuator is not on the truck. The trailer brake controller is on the truck. The thing that actuates the brakes is on the trailer. If it wasn't, the trailer would have no brakes if it broke away.

The magnet in the brake assembly controls the actuator arm in the brake that applies pressure to the shoes that grab the drum. It gets the voltage from the brake controller in the cab. Brake controller, not actuator. Controller.

View attachment 708377

Go back a reread some of the posts he was replying to, and what he replied with. Pretty sure this never said the actuator is on the truck:

DL Meisen​

Please explain where said capacitor are found..... The trailer brakes on my trailer (with 7 pin connector) are controlled by after market controller (below dash) which is actuated off brake pedal switch....

 

[npalen]

oh....

you should have 3 wires, a ground, a stop lamp and a signal lamp( constant on for brakes, and on/off flashing for turn signal. connecting the brake and signal lamp wires would probably make things act strangely with the led drivers in the tail lights.

same as you have a left signal, right signal, and running light wire and ground at the plug.

But the trailer harness has always had just two wires to each light. (white ground and one colored) This worked fine with the old incandescent type.