looking for the chmsl wire on a 16 2500hd

[GlenS]

Trying to hook brake light up on new cap. Anyone know where the wire is? Any post going on here I should read?

[newdude]

Recommendation/Instructions

Follow the recommendations listed below based on the model year of the vehicle.

 

2016-2017 model years

Perform the following recommendations based on vehicle configuration:

1. For vehicles built WITH Under Rail Bed Lighting Option:

   Trucks equipped with the under rail bed lighting option will already have the female side of the X400 connector. Obtain an appropriate length of 18 ga wire to run from the X400 connector up to the CHMSL wiring for the cap or topper. Use terminal part # 60012931 in AFL Tray 21, along with wire seal part # 60994015 in AFL Tray 21 and connect it to one end of the wire. Disconnect the X400 connector and remove the rubber cavity plug in pin position 4 and discard. Install the terminated lead that was just made into the X400 connector pin 4. Run the wire up to the CHMSL for the cap or topper and connect. The ground for the cap or topper CHMSL will need to be made to an appropriate ground.

2. For vehicles built WITHOUT Under Rail Bed Lighting Option:

   Trucks not equipped with the under rail bed lighting option will have a dummy X400 female connector, which will be removed and discarded. The female side of the X400 connector is not available separately, but can be obtained by ordering the under rail bed lighting harness GM part number 23327843. The harness will come with terminals/wiring in pin positions 1 and 6. Remove the wiring and terminal from pin location 1 and discard. Move the rubber cavity plug from pin position 4 and reinstall it into pin position 1. Obtain an appropriate length of 18 ga wire to run from the X400 up to the CHMSL wiring for the cap or topper. Use terminal part # 60012931 in AFL Tray 21, along with wire seal part # 60994015 in AFL Tray 21 and connect it to one end of the wire. Install the terminated lead that was just made into the X400 connector pin location 4. Pin 6 is a ground circuit that is used for the under rail bed lighting and it can also be used to ground the CHMSL for the cap or topper if the wire gauge size in the connector is of the proper size for the CHMSL in the cap or topper. If the wire gauge size is too small, any of the following can be done:

• Make a second wire as described above. Then, remove the wiring from pin 6 and discard. Install the new terminated wire in position 6 for the ground and run it up to the CHMSL for the cap or topper and connect.
• Remove the wire and terminal from pin 6 and install a rubber cavity plug.
• Cut the wire for terminal 6, leaving a couple inches of wire, and seal the end of the wire.

Note: The terminal removal tool for the female side of the X400 connector is J-38125-212.

 

 

[mtushmoo]

The connector is on amazon.

 

https://www.amazon.com/Silverado-Connector-Harness-23295942-23327843/dp/B07C488SBN/ref=sr_1_9?ie=UTF8&qid=1530099338&sr=8-9&keywords=silverado+chmsl 

[w_huisman]

On 6/27/2018 at 6:36 AM, mtushmoo said:

The connector is on amazon.

 

https://www.amazon.com/Silverado-Connector-Harness-23295942-23327843/dp/B07C488SBN/ref=sr_1_9?ie=UTF8&qid=1530099338&sr=8-9&keywords=silverado+chmsl 

This connector is a 6-pin connector.  My 2016 SLT has an 8-pin dummy plug

[mtushmoo]

https://www.gmupfitter.com/files/media/photo/920/UI Bulletin_122b.pdf 

 

According to GM, the change occurred between 2015 and 2016.  

[roadkingrick]

I have a 2015 sierra DD 1500, with bed rail lights. Id like to hook up a new canopy chmsl? #rd brake light and inside canopy lights. since i have the rail lights factory I assume I could wire the dome in and (leaving the cab switch on ) use the dome light to light up the dome and the rail lights on? Has anyone done that before? And the 3rd brake light, the post above says it may already there in the bed rail harness? Otherwise on a 2015 is there a 3rd brake light wire somewhere from factory or do you have to use a logic box and wire from trailer plug or turn signals? I could use any experience you got. Thanks 

[newdude]

15 hours ago, roadkingrick said:

I have a 2015 sierra DD 1500, with bed rail lights. Id like to hook up a new canopy chmsl? #rd brake light and inside canopy lights. since i have the rail lights factory I assume I could wire the dome in and (leaving the cab switch on ) use the dome light to light up the dome and the rail lights on? Has anyone done that before? And the 3rd brake light, the post above says it may already there in the bed rail harness? Otherwise on a 2015 is there a 3rd brake light wire somewhere from factory or do you have to use a logic box and wire from trailer plug or turn signals? I could use any experience you got. Thanks 

 

PIT5314C: CHMSL Wiring for Aftermarket Bed Cap Topper - (Jan 7, 2019)

 

2014-2015 model years

Perform the following recommendations based on vehicle configuration:

1.  For vehicles built WITH Under Rail Bed Lighting Option:

   Trucks equipped with the under rail bed lighting option will already have an X6 connector at the rear body junction block X63A, which will be removed and discarded.   Obtain an appropriate length of 14 ga wire to run from the rear body junction block up to the CHMSL wiring for the cap or topper.  Use terminal part # 1-968857-3 in Lear Tray 7, along with wire seal  part # 828905-1 in Lear Tray 16 and connect to one end of the wire.  Disconnect the X6 connector at the Rear Body Junction Block and remove the rubber cavity plug in terminal position 1 and discard. Install the terminated lead you just made into the X6 connector terminal 1.  Run the wire up to the CHMSL for the cap or topper and connect.  The ground for the cap or topper CHMSL will need to be made to an appropriate ground.

 

1. For vehicles built WITHOUT Under Rail Bed Lighting Option:

   Trucks not equipped with the under rail bed lighting option will have a dummy connector at the X6 position of the rear body junction block. The X6 connector body is not available separately, but can be obtained by ordering the under rail bed lighting harness GM part number 22878806. The harness will come with terminals/wiring in positions 4 and 7. You will need to remove the wiring from terminal 4 and discard. Move the rubber cavity plug from terminal position 1 into terminal position 4.  Obtain an appropriate length of 14 ga wire to run from the rear body junction block up to the CHMSL wiring for the cap or topper.  Use terminal part # 1-968857-3 in Lear Tray 7, along with wire seal  part # 828905-1 in Lear Tray 16  and connect to one end of the wire. Install the terminated lead you just made into the X6 connector terminal 1. Terminal 7 is a ground circuit used for the under rail bed lighting and it can be used to ground the CHMSL for the cap or topper, if desired.  If terminal 7 is not used remove the terminal and install a rubber cavity plug or cut off the additional wiring, leaving a couple inches of wire and seal the end of the wire.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

 

Edited October 13, 2021 by newdude

[mtushmoo]

The six way connectors are back up on Amazon.  I have the 8 pin version available.  user mtushmoo on ebay.