on a recent long distance drive our 2003 2.5t started giving out random warnings the first was alarm service required then it changed gear and put the interior lights on informing us that the rear passenger door was open, this went out with the interior lights as it decided to change gear again when uneccessary, five minutes later it changed gear and warned us of brake failure and stop imediatley, then all instruments went out for the next 40 miles. after stopping at the next services turned the car off and on again to a new warning of airbag sevice required. a trip to our dealer who reset all codes found no fault.he did check battery which is the origonal 10 years old but ok. now the wipers now come on at will and the car still changes gear when not required. please help as dont want to change this car its never gone wrong before like every other volvo we have owned