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Test A: System Does Not Charge

  1. Measure voltage between generator terminal B+ (Black/Orange wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/Orange wire between generator terminal and fusible links "A" and "B" in harness near battery junction box. See WIRING DIAGRAMS  .
  2. Disconnect generator 3-pin connector. Measure voltage between generator connector terminal "A" (Yellow/White wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check ALT fuse (20-amp) in battery junction box. If fuse is okay, repair open in Yellow/White wire or Gray wire. See WIRING DIAGRAMS  . If fuse is not okay, install new fuse and check system operation. If new fuse blows, repair short to ground in Yellow/White wire or Gray wire.
  3. Reconnect generator 3-pin connector. With ignition on, engine off, measure voltage between 3-pin connector terminal "I" (Light Green/Red wire) and ground by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair open or high resistance in circuit between generator and charge warning indicator in instrument cluster. See WIRING DIAGRAMS  .
  4. Measure voltage drop in circuit B+ by connecting voltmeter positive probe to generator terminal B+ (Black/Orange wire). Connect voltmeter negative probe to battery positive terminal. If voltage is .5 volt or greater, repair high resistance in circuit and check system operation. See WIRING DIAGRAMS  . On 3.8L engines, if voltage is less than .5 volt, go to next step. On 4.6L engines, if voltage is less than .5 volts, replace generator. See GENERATOR  under REMOVAL & INSTALLATION.
  5. Restore connections. Start engine. Measure battery voltage and record value. Connect jumper wire between generator terminal "F" and ground. See Fig 1 . Measure battery voltage and compare to recorded value. If battery voltage increased, replace voltage regulator and check system operation. See VOLTAGE REGULATOR  under REMOVAL & INSTALLATION. If battery voltage did not increase, replace generator and check system operation. See GENERATOR  under REMOVAL & INSTALLATION.
    Fig 1: Identifying Generator Terminals
    G94H32141Courtesy of FORD MOTOR CO.
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