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LED tail lights, etc. strange behavior.

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This is just an FYI…

On my 23 year old rig a lot of the lights were dim- running lights - tail lights,etc.  So I have replaced them with LED Lights. Over the last couple of years, I have replaced all the lower running lights and tail lights (turn, brake, running).  I like the LED’s from M4 products- the 1157 bulb is really bright. 

However, all of a sudden the turn lights were not working correctly when the headlights were on.

Each side of my taillights are two (GM?) taillights (one of them is upside down) - so I have two bulbs per side. 

I figured out that with one or two regular 1157 bulb - it was working correctly but with two LED bulbs - it was wacko.  I think the flasher circuit just needs more draw than all LED will provide.

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Since you said that the light's were getting dim,  it sounds like you may have a bad ground somewhere in the light circuits.  I have converted all of my exterior lights to LED's.  Didn't have any issues until I changed the front turn signals to LED's. They did not want to flash.  I just added a load resistor to the both the left and right rear turn signal lines.  I put the resistors on at the rear because it was easier to get to and more room to work.  You can find the LED load resistors on Amazon.  Very cheap.  Just make sure that they don't touch anything the might melt as they can get hot.  As you can see by IMG-4515 they do get HOT!  That fixed everything.  You are correct that the LED's draw so little current that the flasher unit does not want to work correctly.  But the load resistor on both the right and left turn signal lines will fix that.

Good Luck,

Gerry Faulkner

2007 Executive Sandia IV 




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