Check ground circuit Check bulbs they are duble filamented one may be burned out Seems to me there is a wire crossed at the harness. I think the vehicle left turn signal wire is hooked up to the trailer tail lights wire. Usually there are four wires at the trailer harness, yellow, green, white, and brown, The brown wire is usually the tail lights and side marker lights, the white wire is ground, the yellow and green go to the left and right signal lights.
POSSIBLY A BADGROUND
Maybe a short somewhere...did you replace the flasher unit? No - it was blinking spuradically(?) - now I have to blink it manually and it won't blink at all with lights on.
If the lights blink fast on either side of the car then this means you either have non-factory bulbs in the car or you need to replace your blinkers because one of your lights is out.
my left turn signal on my 1997 dodge conversion van works fine,the right signal lights but does not blink,,,,any ideas
grounding. Almost always an inadequate ground for one or other the light assembly or most commonly the ground between trailer and tow vehicle (tongue ground is not enough) - inadequate ground can work with low current loads and behave as if dead circuit with the higher load of additional lamps.
Sounds like you simply have A burned out bulb, Turn the signal on and look at all the lights to see if any are burned out. Could be A marker light if its in the turn signal circuit.
Im not sure i under stand your guestion, but it sounds like the trailer wireing is wrong. The wires on the trailer should be wired like this. White is ground, Green is right turning signal,Yellow is left turning signal,Brown is running lights, Black is brake lights. I hope this helps you.
If both your left and right trailer signals blink at the same time there is something wrong with your wiring harness.
Check your bulbs and your flasher.
If the Avalanche came with the factory trailering package, the trailer lights are separately fused from the other truck lights. Check your fuse panel layout for a 10-amp fuse for left side and a separate fuse for right side turn signal/brake light on the trailer.
Vehicle side, Brown, running lights Yellow, left signal/brake light Green, right signal/brake light Black, ground Trailer side, white is ground
It means that a light bulb is out on the side where the light solid (not blinking) it could be in the front or rear of the vehicle.