LED Fender Mounted Truck Signal Lights not working right

[LJ-TJ]

 i?? Hey Guys, I've mounted LED lights on my mirrors.

Three wires: Red,White and Black.
White is ground.
Red is bright
Black is low lighting.

When I hook up the red wire to the signal light and ground the white wire and turn the turn signal on works great.

BUT when I connect the black wire to the gauge lights and pull them on, the light works great.

But when I turn the signal on the lights go dim and the flash is barely noticeable.

Anybody got any ideas. Hm?

[JDxeper]

TJ
I remember from a few years back about something with the flasher, they make a flasher for the leds something to do with current draw, maybe Tim can help explain.

[ibdilbert01]

What JD is referring to is an electronic flasher, you normally need one if you go completely LED. 

I can't seem to get my mind onto exactly whats causing your issue except maybe a ground issue?

[DaveVA78Chieftain]

As long as the original incandescent lights are still installed, the flasher will not be a problem.  I believe it is due to your connecting to the gauge lamps.  They are driven by a rheostat inside the light switch so they can be dimmed (variable voltage level).  You need to be connected to the regular marker light circuit (brown wire; circuit L10-xxBN).  Since you picked up your marker signal from a gauge bulb, I assume you ran the wiring inside.  So, most Dodge wire bundles run through the floor around the steering column.  In those bundles you will find red and yellow rectangular  connectors.  On the red connector will be a 12 gauge brown wire (standard marker color like used on a trailer connector).  It will only have power on the brown wire when the headlight switch is on.   Tap into that brown wire for the black (dim) lead on the LED lamp.

Dave

[LJ-TJ]

That make cents. Thanks Dave. None of my marker lights on the front up over the windshield work and I haven't been able to find where the wires come into the cabin. All the back s work fine. I remember seeing that connector under the steering wheel behind the plywood by the brake peddle. I'll check it out in the morning. Thanks again.

[ibdilbert01]

They are driven by a rheostat inside the light switch so they can be dimmed (variable voltage level).

Good catch Dave!!!    Didn't even think of that as my 72 just had the dash lights wired to the headlights, no dimmer switch in the mix.

[DaveVA78Chieftain]

You do have the wiring 74-75 Dodge chassis diagram right?  It's available in the free manuals section.  Red mold connector is shown on page 1 at bottom of page.

BTW - As shown on page 2, the Headlight switch drives the presence relay which drives the lamps.  This prevents full current from being pulled through the headlight switch.

Dave

[DaveVA78Chieftain]

LOL Tim.  Darnit, they keep changing things on ya

[LJ-TJ]

 i?? No Luck. When I turn the directional light on it's bright and works great. When I shut it off and pull the light switch on it's dull like I think it's suppose to be. But when I pull the light switch on and put the directional switch on it shows milnimal to not flash. I can here the blinker going but not much if any of a flash. I just bought to new flashers but they didn't make much of a difference.  i?? Sorry guys. Any other thoughts.

[ibdilbert01]

Hooked up this way I don't think you can get a true "flash" mode (on, off, on, off, on...) when the running lights are on.   You should however get (dim, bright, dim, bright, dim...)

[LJ-TJ]

If I don't turn the lights on they work great. It's when I turn the head lights on they barely show a flash.

[DaveVA78Chieftain]

Are you sure you have the wire colors correct for the light assemblies?  It sounds like you have not identified which lead is the ground wire correctly.  What is the brand/model number of these units to find pdf instructions.

My thoughts are, the flasher voltage is a couple of volts either higher or lower than the marker light voltage (produces a voltage differential). When both are ON, the LEDs are only reacting to this voltage diff.

Try connecting both black AND red LED wires to marker light signal (white to ground) and see if you get full intensity. 

If not, then either wire selection is messed up or there is a wiring error in the units.  The white to ground is sort of a European standard rather than US.  US normally uses either green or black as ground for DC circuits.  White is neutral on AC circuits which is where the white is ground thought comes from overseas.

Dave

[DaveVA78Chieftain]

As Tim said, dim, brite, dim, brite when headlights are on.

[LJ-TJ]

 i?? I give up. It's driving me nuts. Thanks for trying to help out. They work fine until I turn the lights on. Go figure.

[maxximuss]

Did you buy just a new flasher or the ones used for LED lighting? They usually have a external ground attachment added on them. such as the Grote one at this site I posted below.

http://www.grote.com/product.php?product_number=44891

[ibdilbert01]

I don't think its the flasher, as Dave said, "As long as the original incandescent lights are still installed, the flasher will not be a problem."

[DaveVA78Chieftain]

They usually have a external ground attachment added on them

When you convert to "LED only lamps" the LED lamps by themselves due not draw enough amperage through the flasher to heat up the bi-metal strip so that it "bends" and breaks contact (turn signal lamp off).  The bi-metal strip then cools off and remakes contact turning the lamps ON.  So, for LED only setups, they provide a ground wire so that enough amperage can be pulled through.  Kevin has a mixture of incandescent  and LED bulbs therefore he does not need the special flasher unit.  He is fighting a voltage differential problem inside of the LED lamps he purchased (typically expensive buggers).

Dave

[maxximuss]

Gotcha!

[ClydesdaleKevin]

I replaced every last exterior bulb on our RV, except the headlights of course, with LEDs, and put in an electronic flasher...and the signal lights still wouldn't work.  Instead of installing resistors in the wiring, I simply left 2 of the front signal bulbs as incandescents, and the problem was solved.

Kev

[LJ-TJ]

 i?? Dave nailed it. I'm guessing I cut the lights into the dash lights. I finally found the directional light wire and the lights seem to work fine.....sort of. The left light works great it even works as a brake light. The right, well it doesn't work as a brake light. The question is do I try to find the problem or do I leave well enough alone. At least there working. D:oH!

[DaveVA78Chieftain]

Well my man the problem is simple.  You picked up the left rear light signal wire (D14-18YE/BK [yellow/black]) instead of the left front signal wire (D12A-18YE [yellow]).  Legally, lights mounted on the mirror (front of vehicle) should not reflect brake light indications.

Dave

[LJ-TJ]

Woooo good man. Thanks Dave. I'll check that out then and get it fixed . The one thing I DON'T want to do when I'm State side is give the boy's in blue a reason to pull me over. Really puts a damper on the day.

[JDxeper]

We'll be looking for those flashing leds!

[ibdilbert01]

Whoohoo!   Can't wait to see them working!!!