Test B: Warning Indicator Is On With Engine Running, System Is Not Charging

1. Measure voltage between ground and generator terminal B+ (Black/Orange wire). See Fig 1 . If battery voltage is present, go to next step. If battery voltage is not present, repair circuit between generator and battery. See WIRING DIAGRAMS  .
2. Disconnect generator 3-pin harness connector. Measure voltage between ground and generator harness connector terminal "A" (Yellow/White wire). See Fig 2 . If battery voltage is present, go to next step. If battery voltage is not present, repair circuit between check ALT fuse (20-amp) in battery junction box. If fuse is okay, generator and battery. See WIRING DIAGRAMS  .
3. Turn ignition on. Measure voltage between ground and generator harness connector terminal "I" (Light Green/Red wire). If battery voltage is present, go to next step. If battery voltage is not present, repair circuit between generator and instrument cluster. See WIRING DIAGRAMS  .
4. Start engine and let idle. Measure voltage between positive battery terminal and generator terminal B+ (Black/Orange wire). If voltage is .5 volt or more, repair circuit between generator and battery. See WIRING DIAGRAMS  . If voltage is less than .5 volts, replace generator.

Fig 1: Identifying Generator Terminals

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Generator Harness Connector Terminals

Courtesy of FORD MOTOR CO,