A coworkers truck 2010 GMC would not start after work last night. When turn key on all lights and radio and heater worked but no starter action. No click. I put booster cables on to see if it would help but nothing happened . The mechanic today said he changed a fuse and it worked. Where would this fuse be? I have not seen a fuse for the starter system before. Mind you most of my fixings are on older vehicles.