Nissan Micra Tailgate?

My mother in laws Nissan Micra 2005, has problem with opening tailgate. I have checked the switch and that works fine. On the plug that goes into solenoid there are four wires. Left to Right...Orange, Black, Orange, Black. There is 12V on first orange and nothing on others no matter if switch is on or off. Is there a fuse that controls this as central locking works ok.
Thanks for any assistance, Dave