Problems with LED taillights

One other problem with LED is if you get the tailights with indicator/brake /tailight in one sometimes one will stop working and you can't just change the offending bulb, you may have to add a light or get a whole new one. Might pay to get individual ones for each function. They don't go forever. Also some cheaper brands will work 12 - 24 volts but not much under 12 v. If your wireing to your tray or trailer is a bit old they may nott light at all if the voltage is too low. An incandecent bulb will still burn if the voltage is low, even if somewhat dim. Not uncommon to see a semi on the highway with no trailer lights. It may be a bad conection, but could also be low voltage that a test light won't show.

I purchased a cheapish set of LED's for my tool trailer and when i opened the packet, the rear of the lights had a sticker on them saying "not suitable for use on more than 12 volt systems"

bigcam, for a novice like me, can you please explain a little more about these resistors, as I'm thinking of putting LED's on my '83 Hino. Thanks. Rod.

I think if the vehicle is "modern" with ADR and all that entails, I'd just stay with bulbs.
But for an older vehicle, I'd run the indicator circuit straight to a relay.
Load that circuit with resistance until the flasher unit cycles nicely and then run the LED indicators from the relay.

Old flasher require resistance to work. Hence why they speed up when a globe goes and slows down with more lights. (or was it the other way around? Doesn't matter in this scenario)

Not aware of any ADR regarding blown globes!

Yes you can get resistors to load up a led system to trick the flasher. And yes maybe a relay with a stack of resistors might work.

But a better option would be to replace the flasher with a new electronic flasher. As I don't believe they are load sensitive. There are also available flashers designed to operate led globes!

Why muck around when the right solution is available!

I put LEDs on a AU Falcon one tonner not long ago and had to run resistors on the blinkers and the brake lights to cure the fast flash and also the brake lights glowing when the ignition is on. I was told that the brake light problem is caused by a low voltage current that runs all the time to test the circuit for blown globes etc. With the globes you can't see it, but it's enough to illuminate the LEDs.

Also, with the Jap trucks with two clearance light switches, the old FSR Isuzus have one on the stalk with the headlight switch, and one on the dash. Apparently the one on the stalk is a CLERANCE light, and the one on the dash is a PARKING light which only illuminates the lights on the rear and sides of the vehicle, not the front.

Grant.

Oh one other point to consider. Led's are a current device. (for the tech savvy they are diodes (Light Emitting Diode)) They don't care to much about volts to illuminate but require a certain current. Yet a normal globe is a voltage device (they are a resistor). Less volts less light!

Hence at the back of a trailer a led works better than a globe. The current needed by a led is low and it doesnt care about the voltage drop of the long cable runs. The globes do!

Whoops sorry Rod, just saw your post.
On an older Hino you will probably only need resistors on the flashers.
I use the Ashdown ones, they are reasonable in size and are easier to mount than some of the others, they will also do 12 or 24 volts.
Once you have fitted them, just get someone to put their foot on the brake with the motor running to make sure it doesn't light up the other lights, if it does you will need 2 resistors on the brake circuit and another 1 on the tail light circuit. Going on the age of your truck though as I said, I reckon you'll get away with just doing the indicators.

Willweld, I've got a BF Falcon ute, I put Hella LED's on it and I got away with just doing the indicators, must have been lucky.

Jeffo is right about the ADR's as well, everyone uses resistors, but you can also use a flasher unit meant for LED's.

The reason that a lot of truck manufacturers still use bulbs is that in the snow, the snow will melt off the light.

bigcam, for a novice like me, can you please explain a little more about these resistors, as I'm thinking of putting LED's on my '83 Hino. Thanks. Rod.

one thing to consider would be the higher the current the better chance there is of a good connection ie a little bit of crap between the two halves of a trailer plug it will quickly burn through and give a good connection were as a low current draw will just do not much a bit like a stick welder welding some rusty surface crank up the amps it will burn through all the rubbish

My idea is hardly original.
Our old Leylands has this system, big old open coil style relays mounted behind the driver's seat.
Didn't matter how many globes you ran on the indicator circuit, they always flashed at the same speed.