GrayGhost_

TSB on this https://static.nhtsa.gov/odi/tsbs/2017/MC-10126990-9999.pdf Bulletin No.: PIT5314BPublished date: 12/21/2017Preliminary InstructionsFollow the recommendations listed below based on the model year of the vehicle.2016-2018 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 appropriatelength 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 AFLTray 21, along with wire seal part # 60994015 in AFL Tray 21 and connect it to one end of the wire. Disconnect the X400 connectorand remove the rubber cavity plug in pin position 4 and discard. Install the terminated lead that was just made into the X400connector pin 4. Run the wire up to the CHMSL for the cap or topper and connect. The ground for the cap or topper CHMSL willneed 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 anddiscarded. The female side of the X400 connector is not available separately, but can be obtained by ordering the under rail bedlighting harness GM part number 23327843. The harness will come with terminals/wiring in pin positions 1 and 6. Remove the wiringand 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 theterminated 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 bedlighting 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 sizefor 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 position6 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.

Thanks for posting. Bulletin only includes the 2016-2017 model years but I've seen quite a few 14-15s in this thread. Are these owners SOL with the warranty on these vehicles? No mention of the 2018 - 2019 (classic) either. I wonder if these got different fuel injectors not to be included also.

This is your friend: https://www.gmupfitter.com/files/media/photo/664/Sierra_Silverado_Electrical_Body_Builders_Manual_Service_Manual_2016_en_US.pdf Looking at the schematic it would seem that the previous owner somewhere disconnected the puddle lamp circuit and jumped the puddle lamps to the headlight circuit. Pin # 8 would insert right next to Pin # 9 (Yellow Wire) and next to pin # 7 which is unoccupied. Technically your puddle lamps should not work at all with that wire disconnected.

My guess would be bcm x7. The Gray / Lt Green striped wire is listed as " Driver Outside Rear View Mirror Puddle Lamp Control " and goes in pin # 8