From past experience, I'd try the following...there is a wiring bundle that goes from each front door into the door frame (encased in a rubber boot, I think). Pull it back from THE DOORFRAME and you will see a connector. You should make sure that this is a tight fit into the other part of the connector - and give it a good spray of WD40. Do this on both front doors. This may solve the problem - if not, it may be that some of the actual wiring has become damaged where it is being repeatedly "bent" with the opening/closing of the doors. That's a bit more difficult, as you can imagine!