yerfdog79

Just got some 3157 leds for my rear taillights. They are awesome bright. However, with the truck off, the function normally, parking lights on, = superbright when apply brakes, a noticeable difference and my third brake isn;t on with parking lights. With the truck running, parking lights on w/third brake light on dim, when I apply brakes theres a not so much noticeable difference. Not nearly as much as when truck is not running. Any thoughts?

CObiker

I know LED's are sensitive to voltage drop. There has to be at least 12 volts at the light. Other than checking for corrosion in the connections, I am not sure of a fix. Is the alternator producing 14.4 volts? Is there some other voltage draw on the system with the engine runnng to cause a voltage drop? Good luck with that one. Electrical gremlins are the worst.

yerfdog79

Upon closer investigation, the LEDs are functioning normally. A couple off and ons of the lights while applying brakes shows no change in brightness. The "not so much" change in brightness with the lights on applying brakes is due to the fact that the LEDs for the running running lights are just really bright. The third brake light being dimly lit while lights are on and engine running is from voltage bleed. Same thing occurs with a couple of my instrument panels lights. I don't mind the third brake light being dim as it gets brighter when brake apllied. Makes it sport of a clearance light. If anyone does LEDs in their instruments I would recommend changing all but the battery, abs and airbag. I would leave those three incandescent as they get voltage bleed and will be dimly lit at all times.

BDavis94

I put led 3157 in my brake lights. With out a resistor in the bulb all it does is make the truck act freaking strange. Look up my thread "strange electrical issues" search it or go through my profile.

yerfdog79

Funny how a simple thing like taillight bulbs can throw off a bunch of stuff. I got my LEDs from superbright and they are the canbus style. The canbus style have a greater intensity and look marvelous in my stock lenses. They say not to use them in non-canbus but I don't see an issue in my application. My voltage bleed has nothing to do with type of led, just the nature of the LEDs themselves to allow lower voltage thru. I am planning on doing the fronts as well. I have an LED flasher to put in when I get the fronts but will have to run little wire extension as the flasher is square and our stockers are round. I will update when I get into that. I have also heard tell that if if you throw an incandescent bulb in the circuit somewhere it can help with the voltage bleed. I would say that would be more of an interior fix though, I wouldn't want to put one incandescent and one led for running lights. As far as I know, I'm not having the issues you are. Just the voltage bleed stuff. My cruise didn't work yesterday, but it has always been weird. Not sure about the horn as I use the one under my nose most of the time. Sorry for the long post.

linkarmy09

any pictures of the LED setup?

yerfdog79

Will try and remember to get some pics this evening

yerfdog79

ABS light on because of ABS issue.

The needles are white, don't know why my camera made them purple with an ora

Will take taillight pics when it isn't raining

yerfdog79

Update: went ahead and put a normal incandescent bulb back up in the 3rd brake light and it fixed some issues. First, now the brake lights are working at correct brightnesses. The abs light doesn't come on any longer. Cruise control works again and the 3rd doesn't stay on dimly any longer. I'm sure a load equalizer would work but I don't want one sitting up in the roof. Hope this helps someone.