LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1999 >> Taurus SHO >> Repair and Diagnosis >> Electrical >> Charging Systems >> Charging System - Generator >> System Tests >> Test A
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test A

  1. Inspect accessory drive belt and tensioner. Repair or replace as necessary and check system operation. If drive belt and tensioner are okay, go to next step.
  2. Inspect battery terminals. If battery terminal connections are loose or corroded, repair or replace as necessary and check system operation. If battery terminal connections are okay, go to next step.
  3. Inspect battery posts for looseness. If either battery post is loose, replace battery and check system operation. If battery posts are okay, go to next step.
  4. Remove battery retaining hardware. Inspect battery case for damage. Replace battery as necessary. If battery is okay, go to next step.
  5. Perform PARASITIC DRAW TEST  under ON-VEHICLE TESTING.. If key-off draw is within specification, go to next step. If key-off draw is not within specification, repair circuit or component causing excessive drain. Check system operation.
  6. Perform BATTERY LOAD TEST  under ON-VEHICLE TESTING. Replace battery as necessary. If battery tests okay, go to next step.
  7. Measure voltage between generator terminal B+ (Yellow/White wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Yellow/White wire between generator terminal and MEGA FUSE (175-amp) in battery junction box. See WIRING DIAGRAMS .
  8. Disconnect generator 3-pin connector. Measure voltage between connector terminal "A" (Orange/Light Blue wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check fuse No. 26 (30-amp) in battery junction box. If fuse is okay, repair open in Orange/Light Blue wire between generator and battery junction box. See WIRING DIAGRAMS . If fuse is not okay, replace fuse and check system operation. If new fuse blows, repair short to ground in Orange/Light Blue wire.
  9. 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 voltage is greater than one volt, go to next step. If voltage is one volt or less, repair open or high resistance in circuit between generator and charge warning indicator in instrument cluster. See WIRING DIAGRAMS .
  10. Disconnect generator 3-pin connector. Measure voltage drop in circuit "A" by connecting voltmeter positive probe to generator connector terminal "A" (Orange/Light Blue wire). Connect voltmeter negative probe to battery positive terminal. If voltage is less than .25 volt, go to next step. If voltage is .25 volt or greater, repair high resistance in circuit. Also inspect fuse No. 26 (30-amp) in battery junction box for high resistance. See WIRING DIAGRAMS .
  11. Restore connections. Start engine. Turn on headlights and set blower motor to high position. Run engine at 2000 RPM and measure voltage drop in B+ circuit by connecting voltmeter positive lead to generator terminal B+ (Yellow/White wire) and negative lead to battery positive terminal. If voltage is less than .5 volt, go to next step. If voltage is .5 volt or greater, repair high resistance in circuit between battery and generator. See WIRING DIAGRAMS .
  12. On 3.0L 4-valve and 3.4L engines, replace generator. See GENERATOR  under REMOVAL & INSTALLATION. Check system operation. On 3.0L 2-valve engines, remove voltage regulator to expose generator slip rings. See VOLTAGE REGULATOR  under REMOVAL & INSTALLATION. Measure resistance between slip rings. If resistance is greater than 10 ohms or less than one ohm, replace generator and check system operation. If resistance is 1-10 ohms, replace voltage regulator and check system operation.
scientia non olet · About LEMON Manuals