1973 ford and led trailer lights :-(

[zingshoen]

i would appreciate some suggestions for the following: i drive a 1973 ford (12 Volt system of course) and recently put LED lights on my trailer. added a high capacity flasher.
now there seems to be a voltage problem. hooked up for testing to a 12 V source, all trailer lights work fine. hooked up to the car i get:

full tail lights
BUT
brake lights dim, work well only w/o tail light
indicators are too dim for use unless i disconnect one of the three indicator lights on the respective side of the car. then they work even when the tail lights are on.

i ve checked the cables, made sure ground is good, with no improvement.
any suggestions where to look next?

[Weldangrind]

Need more info.

Are the factory brake lights also the indicators, or are there dedicated indicator lights at the rear of the car?

Have you tried the setup with the stock flasher?

[zingshoen]

dedicated indicators, but also used as reverse light.

double filament rear/brake lights.

the old flasher did not give better results. i ve been trying to find a bad earth. on the car all the lights are superbright.

***
1973 ford fairmont coupe, like such:

http://4.bp.blogspot.com/_pqLHcqmPe8...h/IMGP2147.JPG

[katoranger]

It really sounds like a ground issue. 40 year old wires may be weak. I think that on a car like you have the light assemblies are grounded to the body by contact with the screws holding them in place and not a ground wire. You may need to make some additional grounds or earths.

Nice car. We didn't get that model here.

[Weldangrind]

You said that you recently put LED lights on your trailer; did it use conventional filament bulbs prior to that, with not trouble? If so, I think you have a back-feed issue.

For me, the key is the dedicated indicators on the car. Assuming that you're using a conventional flat four trailer connector, the colours I'm familiar with are:

Yellow - Left Indicator
Green - Right Indicator
Brown - Tail Lights
White - Ground / Earth

If you connect a flat four trailer harness to a car with combination indicator / brake lights, no special wiring is needed, even with LED bulbs. If you have dedicated indicators, you need a converter box that prevents both indicators from flashing when one is activated. Make sense?

Even if you had a converter box with conventional filament bulbs, it will not necessarily work with LED bulbs. The answer will likely be to add at least two diodes to the trailer harness.

In my case, my van has LED bulbs from the factory, and there was no trailer harness available for flat four, which is what my trailer uses. I used the converter box from my last van, spliced it in and all kinds of weirdness followed. The trailer would work normally, but the LED bulbs in the van did not. IIRC, when I stepped on the brake and activated an indicator, both indicators would flash. There was also back-feeding if I had the headlights on; it was maddening.

I de-soldered a few diodes from some reject circuit boards and put them in the indicator leads (yellow and green in my case). I think I also needed to add a diode to the running light wire (blue), but I can't recall for sure. In any case, my setup seems to be the opposite of yours, but we had similar results. Hope that helps.

That's a beautiful car. I appreciate the hardtop look, with no B-pillars. The Ford Fairmont we had went from '78 to '83, and it was butt-ugly. http://en.wikipedia.org/wiki/Ford_Fairmont

[katoranger]

Weld, I believe you are on to something. I was thinking that the old ford had the basic combination tail/stop/indictator.

A convertor would be needed. My jeep was setup like that and the convertor did not work properly.

[goofyexponent]

What I learned over the years is this. A test light shows voltage by lighting up the light inside. This is great, one strand of wire can provide enough current to light those puppies up.

HOWEVER, Amperage is another thing. If there are not enough amps able to travel through the wire, then the lights do not work. Put a load on the wires. Use a traditional headlight bulb and see if the brakes and signals work. If not, I owuld say the wiring is too far gone to support the needed amps to run the lights.

You say the LED's draw less? You are 100% correct. The draw is now MUCH less and the current has an even HARDER time making it to the lights.

I would try an H3 55watt bulb ...something with a load to it and see if you can get any results.

Hopefully this will pan out for you!!!

[goofyexponent]

This is why I did a MAJOR retrofit to my truck's wiring.

The headlight switch does NOTHING but activate relays.

High beam has one relay good for 40 amp, the same as low beams.

Also, my park lights run on a separate relay...also 40 amps. NO load is transmitted through my $90 light switch in the cab..all the load is carried by a few $3 relays.

This makes trailer witing a BREEZE. One wire to ALL my park lights and trailer markers....and the signal and brake both run through the signal light switch in her.....I am going to install a signal stat switch like the big rigs have so I can leave my signal light on with the truck off and STILL have my keps in my pocket. The signal stat will also hold WAY more load than the factory switch.

I understand the signal stat isn't a good addition to a car, but maybe the relay's are....save a PILE of tracing wires!

[zingshoen]

gentlemen, thanks for your time. :-) i ve been chasing my tail over this for a fair while.

the trailer was a gift and it looked a bit worse than this:

http://4.bp.blogspot.com/_iuhGRUazt5...ightvorher.jpg

after a lot of grinding and painting it looks like this:
http://4.bp.blogspot.com/_iuhGRUazt5...h/imgp3041.jpg

at first i thought the trailer wiring was shot and replaced it with a new LED system. been troubleshooting since.

i won t rule out problems with ground on the car, which is via a screw to the body of the car as katoranger described. i ve tidied up the wiring in the boot, now i ll have to follow the wires through to the front. maybe a bad earth there.
the funny thing is that all the lights on the car are bright and happy.

the trailer lights, when tested with a 12 V source, all light up bright and good.

there s a 7 pin connector, tail, brake, right and left indi are all separate wires! the plug isn t the issue, connecting the trailer wires directly to the resp. wires in the boot gives the same dim results.

voltage loss shouldn t be an issue with LED or is it? if i remove one of the three indicator globes from either side, the LED indicator is bright. but the ground on all three is good, cleaned up, with new globes etc.

[zingshoen]

thanks goofyexponent, that makes a lot of sense. i ll try the trick with the headlight lamp!

[Weldangrind]

I'm still stuck on diodes as the solution.

The trailer looks great! Love the checker plate. 8)

[zingshoen]

i m just getting used to the electrical stuff.

weldandgrind, what did the diodes do? limit the amps?

[Weldangrind]

Think of a diode as a check valve for voltage; they only allow voltage to travel in one direction. IIRC, Spud had to solder in a diode when he converted his bike to LED lighting.

If you have a digital voltmeter laying around, it will tell you which direction the voltage flows through a diode, and it will tell you if a diode is functional. The symbol on a multimeter is an arrow pointing to the right, with a vertical line to the right of the arrow.

Beware that diodes also cut voltage a small amount, so expect less than normal voltage downstream.

[zingshoen]

thanks heaps weldandgrind, i think that may help.

found some general info here:
http://www.carstereo.com/help/Articles.cfm?id=43

what kind of amperage should i look for? 3 amps as it says in the write up linked above, or higher? btw: do you know which amperage spudrider used for his indicators?

what s the best place to solder them in? right near the LED lights, i e at the back of the trailer, or in the boot, where the cables fork off?
i assume you put the inline with the wire, rather than parallel to it.

[zingshoen]

BTW:
in case u missed the movie about the Aussie XB Ford series

lovin the beast