Turn signal after trailer plug install

[Mikeg1988xlt]

My left turn signal on the truck is very dimly flashing if the lights are turned on. If the lights are off it flashes like it should. I followed the install instructions.

 

[tw205]

With or without the trailer hooked to it?

 

[Mikeg1988xlt]

Both hooked up and unhooked

 

[tw205]

Sounds like you have the lights on the left turn signal. I would redress the instructions and review your install.

 

[Mikeg1988xlt]

Thank you.

 

[vigness]

Sounds like a bad / broken ground wire.

 

[Mikeg1988xlt]

I think you're right. After undoing the plug wiring it still dose it.

 

[vigness]

The weak light is indicative of that circuit back feeding to another for a ground. With no power on the back feed, it gets a good ground, power on and it's a bad ground.

 

[RobbieD]

Likely a bad ground.

Did the trailer harness use "scotchlok" connectors that you use squeeze with pliers to make a metal blade "bite" into the wire? These are notorious for damaging the copper wire strands inside the insulation.

 

[Mikeg1988xlt]

Did anyone know you could install the bulb backwards? Because I sure didn't lol. Rewired the new TL socket which was installed a few months ago and was still at a loss. Did some more research and found someone saying the bulb could be in backwards. Thought it was crazy but gave it a shot. Turns out it was crazy enough to work lol. Thanks for the quick feedback.

 

[Snoranger]

Did anyone know you could install the bulb backwards? Because I sure didn't lol. Rewired the new TL socket which was installed a few months ago and was still at a loss. Did some more research and found someone saying the bulb could be in backwards. Thought it was crazy but gave it a shot. Turns out it was crazy enough to work lol. Thanks for the quick feedback.

An 1157 can be installed backward with enough force. The only thing that will happen is the marker light will be bright and the stop/turn will be dim... opposite of normal.
If a 1156 is installed (or a 1157 is installed a little crooked, at the right angle, in a cheap tail light housing) it will short both the marker and turn together. When you turn that blinker on, the marker lights will flash. The same thing can happen if a 1157 shorts internally.