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HOMESERVICE MANUALSMERCURY1994CAPRI XR2, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ELECTRICALCHARGING SYSTEMSALTERNATOR & REGULATORON-VEHICLE TESTINGALTERNATOR OUTPUT TEST
1994 Mercury Capri XR2, Automatic

Alternator Output Test

1994 Mercury Capri XR2, AutomaticSECTION Alternator Output Test
CAUTION: DO NOT ground "B+" terminal.
  1. Start engine and observe charge indicator light. If indicator light does not go out, go to step 2). If indicator light does go out, turn engine off, go to step 5).
  2. Set ignition switch to ON position with engine off. Measure voltage at each terminal. See ALTERNATOR TERMINAL VOLTAGE table. See Fig 1 .
  3. With engine running at normal curb idle, again measure alternator terminal voltages. See ALTERNATOR TERMINAL VOLTAGE table.
    ALTERNATOR TERMINAL VOLTAGE

    Alternator Terminal Ign. ON/Eng. OFF Volts Engine At Idle Volts
    B+ Approximately 12 14.1-14.7
    "L" Approximately 1 14.1-14.7
    "S" Approximately 12 14.1-14.7
    Fig 1: Identifying Alternator Test Terminals
    G93D00730Courtesy of FORD MOTOR CO.
  4. Inspect wiring harness between battery and B+ terminal if voltage check is okay. Inspect remaining charging system wiring if voltages are less than specification. If wiring harness is okay, repair or replace alternator. See Fig 2 .
  5. Disconnect negative battery terminal. Disconnect harness connector from alternator B+ terminal. Connect positive lead of Rotunda Starting and Charging Tester (078-00005 VAT40) to alternator B+ terminal. Connect negative lead to disconnected harness B+ terminal. Set tester to ammeter function. See Fig 2 . Reconnect negative battery terminal.
  6. Connect tachometer to engine. With engine running and all accessories and lights on, press brake pedal. With engine speed of 2500-3000 RPM, alternator output should be 70 amps or more. If alternator output is not as specified, recheck belt tension. If belt tension is okay, repair or replace alternator.
Fig 2: Identifying B + Terminal Connectors
G93E00731Courtesy of FORD MOTOR CO.
RENDER: 1.0x

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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.