How to Install GM Dual Function (CHMSL) Wiring Harness for 2019-2022 Chevy Silverado & GMC Sierra Trucks

Introduction:

This article will be covering the installation of our Dual Function (Third Brake Light Bed Cargo & Reverse) Wiring Harness on 2019 and newer Chevrolet & GMC trucks. This will get the center high mount stop lamp (CHMSL) cargo lights on your Silverado or Sierra to work as both a cargo light and a reverse lamp. This will also enable your rear facing tailgate cargo light (if equipped) to come on in reverse. The trucks cargo lights will also illuminate when you unlock the truck with the key fob at night as a courtesy lamp. This will cause your bed cargo lights (third break light cargo, bed cargo, and tailgate cargo) to operate in reverse. This installation requires no additional tools and will take only 5 minutes to complete.

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For in depth installation instructions, reference the links below:

Link to installation video: 2019 - 2022 GM Third Brake Light Bed Cargo & Reverse Install (DUAL FUNCTION)

Link to technical install document: 2019+ Dual Function (CHMSL) Wiring Harness Installation

Vehicle Fitment: 2019 (new body style) Chevrolet Silverado & GMC Sierra 1500, 2020 Chevrolet Silverado & GMC Sierra 1500 2500HD 3500HD, 2021 Chevrolet Silverado & GMC Sierra 1500 2500HD 3500HD (including Duramax), 2022 Chevrolet Silverado & GMC Sierra 1500 2500HD 3500HD (including Duramax)

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Full Installation Video:

Step 1:

Locate the BCM, which is found under the driver side of the dash to the upper left hand side.

Step 2:

Remove the brown connector and pink connector by pushing the tab inwards and pulling down.

Step 3:

Identify the wire in pin location 26 on the pink BCM connector. On the pink connector, Pin 26 is located on the bottom row, second column from the right. Wire color may vary between vehicles, therefore, pin locations should be your primary reference.

Step 4:

Utilizing the T-taps provided, attach one to the corresponding wire found in slot 26 on the pink connector. For additional leverage, pliers can be used to close T-taps.

Step 5:

Identify the wire in pin location 26 on the brown BCM connector. Pin 26 is located on the bottom row and the first slot from right. Wire color may vary between vehicles, therefore, pin locations should be your primary reference.

Step 6:

Utilizing the T-taps provided, attach one to the corresponding wire found in slot 26 on the brown connector. Make sure to completely close the T-taps for a proper connection.

Step 7:

Once both T-taps are installed, find the blue marked end of the module. The marked end needs to be plugged to the wire tapped into the brown connector. Proceed to bend the flexible module to connect the other T-tap.

Step 8:

Lastly, reinstall the connectors into the BCM. A click sound will be heard confirming the connector has been fully inserted.

Your Installation is now complete!