turn signals dont work when headlights are on

[Nevr2low]

Hey everyone! I'm new to the forum group here. I just bought my '84 K5 about a month ago. I've been fixing a lot of the no so good work the previous owner did since I bought it and doing a few upgrades to as well. I had the grille out the other weekend fixing a few things and decided to put in some LED bulbs in for the markers and blinkers. everything seemed to work right at first, then I drove it at night and the blinker don't work when the headlights are on and the left turn indicator on the dash is on as well. tried a new flasher relay and that didn't do the trick. Not sure where to go from her. Any help would be greatly appreciated

[bd]

Welcome to the site from California.  Sounds like multiple poor grounds for the most part.  Take an inventory of the grounds using the list toward the end of the article, Basics: Vehicle Ground.  Make sure all of the listed grounds are present and that the connections are shiny clean and tight.  Ground is vital for proper electrical function, so don't make any assumptions.

[roundhouse]

Do the signals work fine when the parking lights are on ?
And just have problems when the headlights are on ?

That answer will determine where to start chasing gremlins ,

Also you should consider installing a relay harness for the headlights ,
Several places make them and they really help , it removes the electrical load from the dash and floor dimmer switch to a relay under the hood near the battery
   It makes the lights a lot brighter too


Swap the old bulbs back in and see if that fixes it

Some vehicles just won’t work with LED bulbs

The side markers on the front , blink with the turn signal , and the blinking is opposite of the front signal,
When the front signal comes on , the side marker goes out , it’s done this way from the factory and it works somehow through the ground of the front signal .  Installing LEDs in the front signal can mess this up somehow Because they don’t ground like an incandescent bulb

For the flasher , with LED bulbs , you will now need an “electronic “ flasher

[Nevr2low]

Thanks for the help guys. I found all my grounds and cleaned them up and added a body to cassis ground. None of it fixed the issue. So I started checking out all my bulbs and sockets. I found the right front marker/blinker bulb was all smokey inside, went to change it out and noticed the socket had been replaced at one point with a generic piece of crap. The contacts in the socket were loose and the bulb wasn’t a snug fit in the socket. I found a good quality socket at the parts store, wired it in with new bulbs and everything started to work again. It’s crazy how one little thing can cause so many issues in an electrical system. Thanks again for the help!

[JohnnyPopper]

Fussy little critters those electrons! Never happy at being dragged and pushed around, they sometimes act out...

Glad your life is better now! 'collective sigh of relief'!