The actuator locking the fuel cover on 1995 E36 323i coupe has suddenly failed. No fuses blown, and I confirm when you use central locking there is a 12 volt pulse on the actuator connections which unlocks it (one way) but no reverse pulse to lock it.
I prised the soleniod open to find its just a simple motor with two wire connection that via gears drives a lead screw and no spring return. Therefore to function it must require a +/- pulse to lock and a -/+ pulse to open. Sounds like a stuck relay somewhere. Anyone know where in the electrics this sits or is generated.