Thread: Discovery 3 LED trailer lights

Originally Posted by Tombie

In what context?

Upgrading to LED tail lights? Or for trailer detection?

I'm putting LED's on my 6x4 trailer and wondering if putting resistors on the tail light feed will help, in saying that i think i will probably just make a pulse buster as its almost the same effort.

Re read the whole thread again and a resistor on the brake or tail light circuit isnt required, i need to make this as compact as possible so i can squeeze it in near my compressor with a remote switch.

My understanding is that the car tests for the presence of a trailer through the indicator circuits so I would say no point putting resistors/pulse busters on the tail light circuit.

Certainly my RRS is only on the indicator circuit.

Garry

Originally Posted by 101RRS

My understanding is that the car tests for the presence of a trailer through the indicator circuits so I would say no point putting resistors/pulse busters on the tail light circuit.

Certainly my RRS is only on the indicator circuit.

Garry

Yeah i just read that in here somewhere, i thought it may help with the pulsing but i will build the box with relays instead of adding to the trailers circuit.

Originally Posted by loanrangie

Yeah i just read that in here somewhere, i thought it may help with the pulsing but i will build the box with relays instead of adding to the trailers circuit.

This is what I built. Plugs into the car trailer plug at one end and into the trailer power cable at the other - I just velcro the box to the draw bar - works fine.

PXL_20220201_065859491.jpg

You can see I have the resistors on the outside as they generate a real lot of heat and inside the case things may have cooked.

PXL_20220201_065602155.jpg

The relays on the inside. The D3/early RRS need both resistor and relay on each indicator power line but the D4s are different - I think they only need a resistor on one power line but not sure - D4 people please chime in here.

For flexibility, I did not want mine mounted permanently in the car nor the trailer. One way around all this is to put incandescent globes in the trailer side lights leaving leds elsewhere, the car will pick up the load of the one incandescent globe.

Garry

Interesting set up Garry.. bit of “outside the box thinking”

You are correct on D4 only needing one, but 2 makes the dash symbol consistent!

If you mount the resistors to the inside of the box with thermal adhesive they run cool enough.

I've got the resistors inside the box on the ones I've built, never had an issue, even when some peanut leaves it plugged in all night! It would be best to unplug when not in use for some time.

Originally Posted by Tombie

If you mount the resistors to the inside of the box with thermal adhesive they run cool enough.

But not thinking things through properly - I bought a plastic box from Jaycar and the resistors started to melt the plastic when inside the box. Too tight to buy a new metal box so put the resistors on the outside in the airflow.

Originally Posted by shack

I've got the resistors inside the box on the ones I've built, never had an issue, even when some peanut leaves it plugged in all night! It would be best to unplug when not in use for some time.

When the indicators are not flashing there is no power going through the resistors. So they will never heat over night unless you also left the indicators (hazard lights maybe) running over night.

In other words, not a problem leaving it plugged in when not in use, at least from a heat point of view.