Help with Third brake light on bed cap 2014 Silverado

[Nickshu]

Hi guys I have an ARE bed cap on my 2014 High Country 1500. I have a problem with the third brake light on the bed cap flashing when the brake lights are off. I have tried two different logic boxes without success. I am wired to the left/right turn signal wires at the back of the 7 pin trailer connector.

 

The problem is that the third brake light flashes when either turn signal is on but the brakes are off. When I press the brakes the third brake light stops flashing and goes solid (so the logic circuit is working) but when I let off the brakes it starts flashing with the turn signal again.

 

Any suggestions are appreciated. Thanks!

 

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[Nickshu]

**FIXED**

 

Since it appears no one here knew the answer I will post this for future reference.

 

The shop that installed my cap should have wired it this way to begin with. There is no need for a logic circuit. You just have to tap into the purple/grey wire going into the 30 pin connector at the rear junction box near the spare tire. Note that there are TWO purple/grey wires...you have to find the one that goes to pin 13 on the connector, easy to do with a test light and someone pressing the brake pedal for you. This wire gets power when the brake light is depressed only.

 

Here's a reference: