LED help for 88 GMC sierra

[mannyg]

I posted this from another forum: I replaced all instrument panel bulbs to LED, all are functioning but, the turn signals light up but do not blink. The hazards work , Do i need to change out the flasher to led compatibility? I am needing help please.

[Robznob11]

Yes you probably will. Also note that if you have a led flasher and it does the same thing its probably because your wires at the flasher need to be reversed. The digital flashers are polarity sensitive. I ran into this exact problem when i went all led. I had keep it clean flashers (no load) hazzards worked but turns did not. So i ordered the led flasher with the ground wire and had nothing. I reversed the polarity and what do you know it will work with either of those two flashers. I also tested and found that with out switching the polarity it would work with a load resistor. My conclusion is that
1)no load really means (small load) the load is great enough with all 4 hazzards to blink but not great enough to trigger a blink with only one side.
2) All digital flashers are polarity sensitive. The quickest check is to unpin the metal connectors from the plastic plug where the flasher pluggs in and reverse them. I like to use a jigsaw blade to stick in there to un clip them. Do this before buying additional expensive led flashers! (Note: this does nothing on a traditional flasher if you have all leds you will need a no load flasher, but do this test before ordering 15 different one's to check if they will work)