Is there any way I could wire my reverse lights up so they come on when I have the cargo lights on? Or any other suggestions to be able to see the tailgate/ ground under a little better?
jwagester
I would suggest either:
-wiring in a relay somewhere between the bcm and the fuse boxes, so the cargo light turns on the relay, which then power the reverse light circuit, the way the bcm does it (so it goes through the existing fuse)
-wiring up a relay/fuse to the cargo lights, and to standalong LED lights you mount under the rear of the truck.
https://www.gmupfitter.com/ may have the wiring diagrams you need to do this.
-wiring in a relay somewhere between the bcm and the fuse boxes, so the cargo light turns on the relay, which then power the reverse light circuit, the way the bcm does it (so it goes through the existing fuse)
-wiring up a relay/fuse to the cargo lights, and to standalong LED lights you mount under the rear of the truck.
https://www.gmupfitter.com/ may have the wiring diagrams you need to do this.
I believe this to be the correct information.
for cargo lights on with reverse lights,
backup lights relay control is X5 pin 26 BLU/BRN wire, note, this is a +12V relay control wire, not ground like usual. This relay is labeled the trailer backup lights relay in the schematic. according to the schematic, it is responsible for sending the reverse lights command to the tail light assemblies (for sierra LED tail lights, others may be different)
cargo lights (standing lamp relay control) is BCM X6 (pink) connector, pin 26, BRN/WHT and this also is a +12V signal.
so for cargo lights on with reverse lights
diode jumper backup lights relay control, BCM X5, pin 26 BLU/BRN (+12V signal) to cargo lights relay control BCM X6, pin 10, BRN/WHT (+12V signal), the diode strip goes towards the cargo lights, BRN/WHT wire
note that because of the two different circuits for the cargo lights, this should activate the cargo light on the back of the cab and the "hitch" light on the back of the tailgate, but will not turn on the interior bed lights.
references:
7-256 BCM X6 pinout (cargo lights)
7-255 for BCM X5 pinout (reverse lights)
2-31, 2-32 for backup lights schematics
2-38 for cargo lights schematics
in both cases the only extra load we are adding to the source signal is a relay control, very low current draw. any standard diode will be fine.
for cargo lights on with reverse lights,
backup lights relay control is X5 pin 26 BLU/BRN wire, note, this is a +12V relay control wire, not ground like usual. This relay is labeled the trailer backup lights relay in the schematic. according to the schematic, it is responsible for sending the reverse lights command to the tail light assemblies (for sierra LED tail lights, others may be different)
cargo lights (standing lamp relay control) is BCM X6 (pink) connector, pin 26, BRN/WHT and this also is a +12V signal.
so for cargo lights on with reverse lights
diode jumper backup lights relay control, BCM X5, pin 26 BLU/BRN (+12V signal) to cargo lights relay control BCM X6, pin 10, BRN/WHT (+12V signal), the diode strip goes towards the cargo lights, BRN/WHT wire
note that because of the two different circuits for the cargo lights, this should activate the cargo light on the back of the cab and the "hitch" light on the back of the tailgate, but will not turn on the interior bed lights.
references:
7-256 BCM X6 pinout (cargo lights)
7-255 for BCM X5 pinout (reverse lights)
2-31, 2-32 for backup lights schematics
2-38 for cargo lights schematics
in both cases the only extra load we are adding to the source signal is a relay control, very low current draw. any standard diode will be fine.
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