Port electrical switch isn’t working

[Lucasg 0]

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? 
 

[Troy 234]

check power and ground at the switch.  Unplug both the port and starboard or center and check power and ground. IF both are good ohm check the wires to the out pump (easiest) and make sure the wires are good. Sounds like a power/ground issue.

Use the working switch connector to figure out which switch wire is which for the non-working switch.

Edited January 9, 2020 by Troy