2004 4.2L Trailblazer EXT - Blower motor not working on Fan position 5, works on all others 1,2,3,4. No voltage at blower motor resistor from 40A fused circuit and fuse 35 is good under hood. Voltage is at fuse but not at connector on blower motor. i get voltage on relay when on fan position 5. a break somewhere in wiring? cant trace back! how do i check or rewire with another 12v source? HELP!