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HOMESERVICE MANUALSFORD1999MUSTANG GT, 2D CONVERTIBLE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM & COMPONENT TESTING - EEC-VCOMPUTERIZED ENGINE CONTROLSPOWERTRAIN CONTROL MODULE (PCM)GROUND CIRCUITS
1999 Ford Mustang GT, 2D Convertible, Standard

Ground Circuits

1999 Ford Mustang GT, 2D Convertible, StandardSECTION Ground Circuits
  1. Turn ignition off. Locate PCM. See POWERTRAIN CONTROL MODULE LOCATION table. Using a DVOM, check continuity between ground and PCM connector pins. See IDENTIFYING PCM GROUND PINS. See Figure. If continuity does not exist, repair open ground circuit as necessary. If continuity exists, go to next step.
    IDENTIFYING PCM GROUND PINS

    Application PCM Ground Pin No.
    Continental, Crown Victoria, Grand Marquis & Town Car 3, 25, 51, 77 & 103
    Contour, Cougar & Mystique 24, 51, 77 & 103
    Econoline
    4.2L & 4.6L 24, 25, 51, 76, 77 & 103
    5.4L 3, 24, 25, 51, 77 & 103
    6.8L 3, 23, 24, 25, 51, 76, 77 & 103
    Expedition & Navigator 3, 25, 51, 77 & 103
    Mustang 24, 25, 51, 76, 77 & 103
    3.8L 24, 25, 51, 76, 77 & 103
    4.6L 2-Valve 3, 25, 51, 77 & 103
    4.6L 4-Valve 25, 51, 77 & 103
    Pickup
    F150 & F250
    4.2L & 4.6L 24, 25, 51, 76, 77 & 103
    5.4L 3, 25, 51, 77 & 103
    Super-Duty Models 3, 23, 24, 51, 76, 77 & 103
    Ranger 24, 25, 51, 76, 77 & 103
    Sable & Taurus 24, 25, 51, 76, 77 & 103
    Taurus SHO 3, 23, 24, 25, 51, 76, 77 & 103
    Windstar
    3.0L 24, 51, 76, 77 & 103
    3.8L 24, 25, 51, 76, 77 & 103
  2. Touch negative lead of voltmeter to a good ground. With vehicle running, backprobe positive lead of voltmeter to each ground terminal. Voltmeter should indicate less than one volt. If reading is greater than one volt, check for open, corrosion or loose connection on ground lead.
RENDER: 1.0x

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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.