My 03 reg E 320 diesel is playing up and I don't know why. The message "Electrical conductors turned off" comes and goes regularly, as does a message telling me that "Electrical conductors are now switched on". The car starts and runs OK, but I'm reluctant to go any distance from home as both my wife and I have mobility problems and need to guarantee that we can get home again. A non official dealer has had a go at correcting the faults, but I don't know what he did because the used car dealer I bought the car from arranged the work. Any ideas, preferably in" Janet and John do electronics" language?