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HOMESERVICE MANUALSFORD1999MUSTANG GT, 2D CONVERTIBLE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ELECTRICALGAUGESINSTRUMENT PANELS - ANALOGSYSTEM TESTSTEST Y: HEADLIGHT WARNING CHIME DOES NOT OPERATE PROPERLY
1999 Ford Mustang GT, 2D Convertible, Standard

Test Y: Headlight Warning Chime Does Not Operate Properly

1999 Ford Mustang GT, 2D Convertible, StandardSECTION Test Y: Headlight Warning Chime Does Not Operate Properly
  1. Check headlights and exterior lights operation. If all exterior light operate properly, go to next step. If all exterior light do not operate properly, repair as necessary. See EXTERIOR LIGHTS and HEADLIGHT SYSTEMS articles.
  2. Connect New Generation Star (NGS) tester to Data Link Connector (DLC). Turn ignition switch to RUN position. Monitor Generic Electronic Module (GEM) PIDs IGN_KEY, IGN_S, IGN_R and IGN_A while cycling ignition switch through all position. If PIDs agree with ignition switch position, go to next step. If PIDs does not agree with ignition switch position, perform TEST V: KEY-IN-IGNITION WARNING CHIME DOES NOT OPERATE PROPERLY  .
  3. Using NGS tester, select GEM active command CHIME. Trigger CHIME active command on and off. If chime operates properly, go to next step. If chime does not operate properly, go to step  9 .
  4. Using NGS tester, monitor GEM PID D_DR_SW while opening and closing driver's door. If PID agrees with door position, go to next step. If PID does not agrees with door position, perform TEST X: DOOR AJAR WARNING CHIME DOES NOT OPERATE PROPERLY  .
  5. Using NGS tester, monitor GEM PID PARK_SW while turning headlight switch to ON and OFF positions. If PID does not agree with switch position, go to next step. If PID agrees with switch position, go to step  9 .
  6. Using NGS tester, monitor GEM PID PARK_SW while turning headlight switch on and off positions. If PID does not always indicates ON, go to next step. If PID always indicates ON, go to step  8 .
  7. Turn ignition switch to OFF position. Disconnect GEM harness connector C352 and headlight switch harness connector C228. Measure resistance in Brown wire between terminal No. 7 at GEM harness connector C352 and terminal "R" at headlight switch harness connector C228. See Figure and Fig 1 . If resistance is 5 ohms or less, go to step  9 . If resistance is greater than 5 ohms, repair open in Brown wire.
  8. Turn ignition switch to OFF position. Disconnect GEM harness connector C352. Ensure headlight switch is off. Turn ignition switch to RUN position. Measure voltage at terminal No. 7 (Brown wire) at GEM harness connector C352. See Figure . If voltage does not exist, go to next step. If voltage exists, repair short to voltage in Brown wire.
  9. Disconnect all GEM harness connectors. Inspect connectors for pushed out pins or corrosion. Reconnect all GEM harness connectors, ensuring they are correctly connected. Operate system and verify is concern is still present. If concern is still present, replace GEM. If concern is not present, system is okay at this time.
Fig 1: Identifying Headlight Switch Harness Connector C228 Terminals
G99F08206Courtesy of FORD MOTOR CO.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.