F18 Fuse Blowing C5 02 64k. No Start.

[Guest gaztank]

The f18 fuse protects the auto box switch, fly wheel angle sensor and diagnostic socket. In the last 2 weeks this fuse has blown twice on a friday each time. The car would not attempt to start if it did not know what angle the fly wheel was. When the fuse is blown the ignition will come on as normal and on turning the key nothing happens but you cannot move the gear shift when the brake peddle is depressed out of the park position. I have checked the local wires in the fuse box, i am yet to check the looms near the brake peddle.the weather conditions were damp and misty the first time and raining the next. Does the fuse protect anything else, would the sensors in the worn brake pads touching earth effect that circuit or a bulb in the rear light cluster. I need somebody who may experienced this problem or somebody from citroen to help me.If nobody can help me I will need to go to the local citroen dealer to get the diagnostics and electrics tested. once the fuse is popped in it starts fine and works ok for a week and then suddenly pop. another fuse blown, if the fault was always there then i might find it quicker, that is the problem with intermitant faults it could work ok for weeks for all i know. i have scanned the forum for similar fault with no luck yet. funny thing is the car is working fine all day,with no hint of a fault you stop it park up for 10 minutes get in the car turn the key not touching anything else and it does not start. please help me gary.

come on guys any ideas