Fuel flap release mechanism actuator 3B0810773B

[jackshaft]

My Passat B5.5 Estate fuel-cap flap failed to open with the driver’s door switch so I removed the fuel flap release mechanism actuator (3B0810773B) and it tested OK. There’s about a 11.25V reading on the red-green positive wire on the actuator connector when the switch is activated and the same on the red-blue positive feeding the switch but there’s not enough current to light a 12V bulb. I can only assume that there’s a relay involved but I have been unable to find any reference to one. I’d be grateful for any help to solve the problem before I bypass the switch and fit a momentary push button in the luggage compartment. Many thanks.