Auto led too bright?

[Garagebound1]

I'm building a completely new dash and have used led bulbs for oil pressure, turn signal indicators and hi-beams. The problem I'm having is with the hit beam indicator light. It lights up really bright when his beans are on but on low beams its still lit albeit slightly dimmer. Would a resister in line fix problem and if so what size resister?

 

[AffableCurmudgeon]

It may, but the value of the resistor depends on led drop voltage and the current that it needs.

 

[Citation]

How are the current LEDs setup? Is this a 12V system where LEDs have been used with a simple current limiting resistor? You can look at changing the LED out for a different, dimmer model (with a correct current limiting resistor).

In general, yes, changing the resistor will dim the LED but that's not really how LEDs are meant to be used. A bit more information on the rest of the setup might help.

 

[Garagebound1]

I used a Ron Francis wiring harness and purchased small chrome rimmed 12 vdc led indicators. The turn signals are fine but when changing from high beams to low the indicator (blue led) just dims slightly. It doesn't go out. I'm using an Ididit steering column as well as the relay box that I can hear click with switch. High beam indicator is really bright when high beams are on.

 

[ttpete]

I'm building a completely new dash and have used led bulbs for oil pressure, turn signal indicators and hi-beams. The problem I'm having is with the hit beam indicator light. It lights up really bright when his beans are on but on low beams its still lit albeit slightly dimmer. Would a resister in line fix problem and if so what size resister?

The dim light on low beams is probably from a bad ground, usually at the headlamp. Check the ground wires at the point where they are fastened to the body metal.

 

[Garagebound1]

No body metal. Fiberglass, but I put a ground buss bar under dash and all items are grounded there and to another in trunk and then directly to battery ground and engine block. Someone told me that most of these leds are 3 volt dc so I'm thinking with a resister it might drop the volts down enough to extinguish the low beam light. Just don't have any specs on less to size resister.

 

[NFT5]

The fact that the LED is on at all with low beam is an indicator of a wiring problem that needs to be corrected first. Once you've done that you can address the issue of the high beam being too bright for comfort, which would, ideally, involve changing the LED and resistor.

 

[Innovate1]

As others have said I think the LED should go out on low beam. Use a voltmeter and measure the voltage at the LED when on low beam. Depending on the color an LED takes over a volt to turn on so anything less than that shouldn't turn it on. A resistor in series will only dim it a bit more. If you use one to dim the high beam I think you will still be able to see the LED on dim on low beam. I suggest you put a diode or zener in series. A diode has about 0.7V drop. A common 1N400x series will work. Last digit is the voltage rating and any one will work. You probably want more dimming than that so a zener will work. I would try about 2 or 3 volt, 500mW part. Adjust for desired light level on high and it will also eliminate low glow on low beam.

 

[Citation]

Was this system designed to work with incandescent lights? Sometimes, for what ever reason a system might be designed to run some current through the lamps at all times. The current is low enough to not illuminate an incandescent lamp but will light an LED.

 

[ttpete]

If a vehicle has CANbus systems, lighting can be entirely different. They sometimes furnish 12V continuously to the lights and control them by switching the ground side on and off.

 

[Wrench97]

Being lit with the lows beams on reminds me of issues we use to have with mechanics puting 9007 bulbs in Macks that took 9004 bulbs.
The bulbs are the basically the same except the ground terminal is in a different position causing the bulb to pull the ground through the indicator lamp and lite it up dim.

 

[Garagebound1]

This is a kit car Cobra and I'm using a Ididit column dimmer is in the tilt knob and it came with a stainless box with wiring diagram to hook everything up. I'm assuming its some sort of relay setup but sealed. I'm also thinking that it was supposed to be used with incandescent lights but liked the tiny chrome trimmed leds. Dealer said they were 12 volt but no specs and I bought them so long ago I'm not sure what company. I'm thinking that they're so sensitive to lower voltage that the low beam still lights. I wasn't sure who to call as there are so many manufacturers involved. I was hoping this had been done before and I wouldn't have to experiment. Guess I'm going to have to pick up some diodes and resisters

 

[PhantomEB]

It’s a toy…. not like you out there annoying everything daily!

I have LED headlights and if someone thinks that’s too bright to flash me, the light bar switch is inches from my fingers…..

 

[couch67]

It’s a toy…. not like you out there annoying everything daily!

I have LED headlights and if someone thinks that’s too bright to flash me, the light bar switch is inches from my fingers…..

OP is referring to the high beam indicator on the dash, not the headlights.

OP, you might be on to something with the relay setup and originally intended for incandescent bulbs. If the setup is using solid state relays, the leakage current in them when in the off position (ie low beam), can be high enough that the LED is lighting up a bit since the it consumes so little current. The zener mentioned earlier will most likely work.

 

[Citation]

Assuming the system is working correctly, another option would be add a series resistor to the lights. It will dim the LEDs. You might have to experiment with the right values. Depending on your electronics confidence you might be able to set up a simple circuit to switch the LEDs instead of a relay.

 

[Chumly]

I agree that when on low beam it's still slightly lit at all is a wiring issue. It should be in O-F-F mode. To me 12v is 12v, a switch is a switch, and an LED is a Diode that needs forward bias voltage so I'm a bit perplexed.

I remember blue LED's demanded 5V while all the others were much lower (and how this LED got down to whatever voltage is built in), but that's also generic LEDs and not a socketed one. I don't know how an LED is half forward biased and dim. To me, logically, they're on or off. Yes there are dimmable LED's but this shouldn't be one of them I'd think. I've got dimmable LED's in the vehicles but they're not dim while off.

Thinking outloud, it's a process: Is it possible you have a pretty nice question about a single bad LED? Probably not, put possible. Stick another LED in there and see what happens. Thinking cheap and easy here. Then I'd pull the thing, stick meter probes in there or go at the backside and see the voltage on high and low beam. Low should be zero I'd think so why is any power at all going to the socket on Dim to even illuminate it? Relay should be an open contact while on low and you may really want to drill down on that relay and see if it's leaking. I also don't like that it's "super bright" while on high if all the rest are blue LED's and this one LED stands out above the rest. Current/Amps is unknown and must be measured in Series which I suppose you could do from the back of the dash. Why is that relay sending anything to the socket? It's bugging me now.

If you can't figure it out, I'd give up on the Cobra Kit car and I'll take over once you send me the title taped to a Coyote crate engine

 

[Citation]

LEDs can vary in brightness depending on the current going through them. Typically an LED is spec'ed to have a given voltage drop (say 1.8V for red) at a given current through the LED (say 70mA). This is a hypothetical red LED (hypthetical but realistic numbers). If the current flow through the LED is higher than 70mA, say 100mA the output will be brighter but the LED life may be significantly shorter. The rated current and voltage is picked because its either the brightest level with reasonable life or the most efficient output level.

If I take my red LED and up the current to say 200mA I will probably burn it out. If I drop the current to say 10mA the output will be dimmer but it may still illuminate. At that current the voltage drop may be 1.5V. My kids have some cheap LED flashlights. These are the ones with a simple current limiting resistor and powered by 2AA batteries. They go from bright to dim rather quickly but it amazes me how long the things can go (literally days) at low output with near dead batteries. So instead of the 3V from new AA cells, the light is running on 1.8V from two very low batteries.

One option the OP could take is to add an additional resistor to further limit the current to the light. It will dim the light when on, and further dim the off state.

Finally, I wish I had an example but I think it is worth stressing, the circuit might actually be designed to work this way. It's possible this system was designed to send some small amount of current through the intended incandescent lamp at all times. That current would be used to power or sense something in the system. This might be done with a large resistor in line with the lamp. Thus the lamp never gets enough current to visibly light but current still flows. When the high beams are turned on the resistor might be shorted thus full current to the lamp.

Side:
I'm not sure that everyone understand what a current limiting resistor is. Taking my LED example, I need 70mA and 1.8V through my LED. The car is providing 12V. Clearly 12V is too much. However, with the right resistor I can limit the current flow through the resistor to just 70mA. I take 12V - my 1.8V voltage drop across the LED. That gives me 10.2V that I need to drop via the resistor. V=IR, I want I to be 70mA (0.07A), and I want V=10.2. So the resistor that will limit my current to 70mA is 10.2V/0.07A=146ohms.
Here is some more information about current limiting resistors.

LED Current Limiting Resistors - SparkFun Electronics

www.sparkfun.com

 

[Citation]

OK, looking at some threads relating to Toyota lighting it does appear that at least some Toyota models put the high beam indicator in series with power that went to a relay or something. When owners switched the headlamps from incandescent to LED headlights (presumably with a relay?) they found the high beam indicator no longer worked correctly. Several of the posters tried to explain how things were wired. Either way, it sounds like the old lighting systems were actually counting on the resistance and current draw of various incandescent bulbs to function correctly. This might be kind of like the way a turn signal relay flashes faster if a lamp is out (at least on older cars).

High Beam Indicator not working after LED headlight upgrade

I just upgraded my headlights with a set from Amazon (New Brights LED Headlight Conversion Kit - 80W 6400LM Cree LED). The low and high beams work...

www.tacomaworld.com

https://www.toyota-4runner.org/3rd-gen-t4rs/263289-high-beam-indicator-what-triggers.html <--- look at post #3 and post 5 where they say the Toyota high beam indicator is actually more like a "low beam not on" indicator. Given the way this Toyota diagram works, there may be enough voltage drop over the headlight wires to result in voltage to light an LED even when the low beams are on. That wouldn't be an issue with an incandescent lamp.

Have high beams but indicator does not light - YotaTech Forums

86-95 Trucks & 4Runners - Have high beams but indicator does not light - It seems I've found my first problem on my '91. The blue high beam indicator does not light when flipping the switch. I've had the cluster out and the bulb is fine. I went and switched between bulbs in it to confirm if it...

www.yotatech.com

 

[Citation]

OK, from post 5 in my link above here is a wiring diagram from a Toyota truck headlight circuit

https://www.toyota-4runner.org/attachments/3rd-gen-t4rs/314414d1539014481-high-beam-indicator-what-triggers-headlight-usa-pdf?s=1fb7b6cd21f94cc9e04bd338ff33de2f

I'm going to assume the OP's system is similar.

When either beam is on pin 3 on the lamps are connected to 12V. To actually illuminate the beam (high or low) pin 1 or 2 needs to be grounded. The multiway switch, shown as a blue box in the lower left connects the lamps to ground to cause them to light up. I've drawn a crude green line to show the path the current takes in low.

When the high beams are on, the headlight pin 1 is not connected to ground (thus the low beams don't turn on). However, that pin 1 is connected to the high beam lamp. Thus the current that lights up the high beam lamp actually flows through the headlight filaments. If both low beams were blown the high beam indicator wouldn't illuminate.

When you are in low beam the lamp pin 1 is connected to ground. If the system worked perfectly that would mean voltage at pin1=0 thus voltage at the high side of the indicator lamp would also be zero. In real life the headlights draw a lot of current (around 8 amps going through that wire through the light control switch). It doesn't take much resistance to cause a voltage difference across that high beam indicator lamp. The OP might take the lamp out and measure the voltage across the pins when the low beams are on. If it's say 2V that isn't going to cause a 12V indicator lamp to light up but probably will visibly illuminate a far more efficient LED.

Looking at the Toyota wiring diagram, there is nothing wrong with the system, it was just designed to operate with incandescent lamps that pass small current and won't illuminate with low voltages.

I would start with trying to add a resistor in line with the LED. I can't say what value other than likely under 100ohms but it would be guess and check. A variable resistor/pot in the 0-100 or 0-1000 ohm range might be useful for guessing. Dial the right amount of resistance in then measure the resistance to see what worked. Take that resistance and recreate it with 1/4 watt resistors.

Alternatively, wire a relay into the high beam indicator circuit and use it to switch the actual high beam LED.

 

[tdkkart]

I've got probably the same LED lamps in mu street rod, and yes, the blue one was obnoxiously bright.
I think I ended up with a 22k ohm resistor in series with the LED.

Mine looked like these:

Universal Dash Indicator LED Light Bulb Kit, 5/16 Inch,Green/Blue

Light up your dash and stay aware of your vital engine temperatures and pressures utilizing our Universal LED Indicator Bulbs. These simple to install and wire single LED's can be used throughout any build - commonly found up on the dash for warning lights or turn signal indicators. Let your...

www.speedwaymotors.com

 

[Innovate1]

I've got probably the same LED lamps in mu street rod, and yes, the blue one was obnoxiously bright.
I think I ended up with a 22k ohm resistor in series with the LED.

Mine looked like these:

Universal Dash Indicator LED Light Bulb Kit, 5/16 Inch,Green/Blue

Light up your dash and stay aware of your vital engine temperatures and pressures utilizing our Universal LED Indicator Bulbs. These simple to install and wire single LED's can be used throughout any build - commonly found up on the dash for warning lights or turn signal indicators. Let your...

www.speedwaymotors.com

22k in a 12V system gives less than 1 mA of current. Seems like that would be very dim. Maybe 2.2k?

 

[tdkkart]

22k in a 12V system gives less than 1 mA of current. Seems like that would be very dim. Maybe 2.2k?

What is "dim"? No cut and dried answer here, try it, then adjust as needed.

 

[Citation]

22k in a 12V system gives less than 1 mA of current. Seems like that would be very dim. Maybe 2.2k?

I would guess more like 22 ohm since there is already a current limiting resistor in there.

 

[Garagebound1]

Man you guys have given me a bunch of good directions to go. I was going to post on a like Cobra forum but every time a question comes up on Garage journal, there's always an answer (or 20). Tonite I finally got the turn signals working. There was a pin out of place (in a factory plug) that's got pretty much all the wiring gremlins taken care of, tomorrow nite I'll dig into the relay and leds for headlights. I like the potentiometer idea, that should save a bunch of time. I think I'm going to hook up an incandescent light as well just to see if it functions properly.. Thanks guys!!

 

[rburke65]

Oncoming traffic …They blind me at night!

 

[Uofime]

Did ididit provide a schematic for the column, switches, relay box and the same question for the wiring harness to the lights?

 

[Chumly]

"what is DIM". I think we need to again correct and adjust. "DIM" means the LED indicator that the headlights are in "ON mode" or "HIGH mode".

High Beam Head lights have this LED in SUPER BRIGHT mode and DIM mode have this indicator glowing DIM.

So my post here is what everyone in the world should see: When your headlights are bright, you get a light on your dash that lights up the "Bright" headlamp indicator. When you are on dim, you get nothing. Well, OP gets SUPER bright on high and something on dim headlights.

I would expect and like NOTHING while the headlights are normal and dim. No dashlights at all saying my headlights are on. Beat me up if I'm wrong, I'm an EE too...but go out and start up your vehicle, and look at the dash. Turn the light on, hit the high beams: you get a blue high beam (his are super bright). Now turn off the high beam, nothing (he has a dim LED and still illuminated when there should be nothing lit.)

A corvette guy should know right off the bat, but that ain't me..that was dad playing with floating grounds in a fiberglass body vehicle. And I still want him to just give me the Cobra kit car with a Coyote crate engine!

There's a lot of multi-meter probing to do here as other things my pop up as the build starts seemingly wrapping up. Gauges start going wonky are very likely next if this one step isn't fixed.

 

[Garagebound1]

Uofime, I didn't get schematics with column which came with dimmer switch in tilt lever and relay box. I'm going to call them with questions.
Chumly, thx for the explanation, you're right about indicator condition, I disconnected harness to all indicators and I have 12.6vdc while on high beams, on low beams 6 vdc. I'll know more after a phone call to Ididit.
As for handing car over, you wish! I've been slowly accumulating money, skills and knowledge since I bought it in 1994. My garage collapsed from snow load just before delivery, then company was going thru bankruptcy so I didn't get half the parts, then I started paying for 26 surgeries for my daughter. I'm finally seeing the light at the end of the tunnel. Working out gremlins and upholstery are all that's left. But I appreciate the help and the offer.