I have a 2008 Avalanche that does nothing when flipping the Port switch to fill or drain. I have checked all the fuses and checked for power. Assuming I’m using the multimeter correctly I’m getting power to the port harness. I have unplugged the port switch and plugged it into the center wiring and it works so I don’t think the switch itself is bad. I’m not sure what else to try. Any ideas on what to troubleshoot next?