Can You Use The 3rd Brake Light Logic Module With A 4-Pole

Updated 04/09/2024 | Published 10/25/2021

Question:

I purchase a 20-702 3rd brake light logic module. Can I use a 4 flat trailer connector with product? I dont want to splice into factory wiring of my 2021 chevy silverado.

asked by: Michael M

Expert Reply:

For your 2021 Chevrolet Silverado you will have to splice into the factory wiring to use the 3rd Brake Light Logic Module # PP20-702 to connect the left and right turn signals, along with the green wire.

You can also combine this harness # PP20-702 with a 4 pole harness like the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector # HM38138.

expert reply by: Bryce D

3rd Brake Light Logic Module Install Instructions
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3rd Brake Light Logic With 4 Pole
(click to enlarge)

Will

4/7/2024

I am trying this exact setup today. While the break light doesn't blink when the breaks are applied with a turn signal, the light is blinking when I remove my foot from the break with either turn signal on. Is my new module faulty?

Bryce D.

4/8/2024

@Will Not necessarily, what you're describing sounds like a grounding issue so I'd suggest checking the connection of the main ground wire of the trailer wiring harness. You'll want to make sure it is attached to a clean metal surface, or if not you can run all of the trailer wires back to the main ground.

Will

4/8/2024

@BryceD initially tried using the 4 way pin connector but have now tried going straight to Truck frame for ground but still blinks

Bryce D.

4/9/2024

@Will Interesting, it sounds like there may be some back feed from the brake circuit. I recommend installing some a diode # RM-690 on the brake wire to fix it.