VEHICLE OFF, LOCKED AND PARKED IN DRIVEWAY. NOT USED FOR 7 HOURS. ELECTRICAL SHORT IN ENGINE COMPARTMENT STARTED A FIRE. IN DISPUTE WITH GM AS TO WHAT CAUSED SHORT. THEY DENY RESPONSIBILITY AND SAY IT WAS AN AFTERMARKET ELECTRICAL ACCESORY THAT WAS INSTALLED 1 1/2 YEARS AGO, BUT GM WILL NOT PROVIDE A COPY OF THE INVESTIGATOR'S REPORT TO ME OR MY INSURANCE COMPANY. *AK