Preliminary Inspection

Check for broken or partially broken wire inside insulation, which could cause system malfunction, but prove good in a continuity/voltage check with system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring voltage drop with system operational (under load). Check power mirror system related fuses. Check and ensure grounds are clean and tight. See WIRING DIAGRAMS  . Check for proper installation of aftermarket electronic equipment. Correct any obvious problems before continuing testing. If problem still exists, perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.