Ground (aka Earth) is the return path for the 12V dc system. It is the chassis of the vehicle. One conductor takes the 12V positive to the trunk (aka boot) latch solenoid. The negative conductor from the solenoid is connected to vehicle ground. If that connection is open circuit, the solenoid will not operate, even if the positive side is energised by operating the latch release ( I assume you have checked that that happens?)
Hmm the negative is connected to ground (ie the car body) as well as threaded somewhere else into the car, presumably the interior). But I’m unable to determine if anything looks wrong on initial visual inspection. I have my service appointment with Kia tomorrow anyway and have already notified them that this has happened so they’ll investigate as well… thanks for your help though!
