GMC Sonoma - left turn signal and real tail lights (not brake) are possessed

[Thomas Shelby]

Would love it if someone can help me with this. I've been at it for hours.

 

2003 GMC Sonoma single cab.

Wife is driving it and suddenly two things happen:

left turn signal is always on, won't blink

tail lights (not the brake lights) won't turn off.

 

So I check fuses and replace the combo switch.

that's not it. So I remove the new switch. Tighten the junction box back up.

 

And - voila - it works. NFI why.

 

Then, 2 hours later, without anyone touching the truck, the tail lights are back on.

 

Replace the turn signal flasher.

 

Everything works! Tail lights and turn signals!

For exactly 20 seconds.

 

Now the tail lights are back on, and the left turn signal half blinks - it's always on, but when it should be blinking off it blinks to half strength.

 

I can't set the truck on fire. I've thought of it, but it's not mine.

How is it that turn signal wire and tail light wire are shorted together? where is that turn signal getting power from? wtf happened?

 

I like problems with big chunks of metal, not thin strands of copper.

[Niners 365]

Have you checked the ball switch located in rear by the main connection junction? If this goes out, it will cause tail lights to malfunction. Also check your ground clscrews where lights are attached. If those are corroded or busted off it will cause symptoms your getting.

  There are youtube videos that show you where they are at.

[dna9656]

When it's freaky and electrical ALWAYS suspect bad grounds. Electricity WILL find a way back to the battery SOMEHOW.