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HOMESERVICE MANUALSFORD1987ECONOLINE E350, VAN WINDOW, 7.5 LREPAIR AND DIAGNOSIS (SINGLE PAGE)ELECTRICALCHARGING SYSTEMSALTERNATOR - MODELS W/INTEGRAL REGULATORBENCH TESTINGOPEN FIELD OR SHORT CIRCUIT TEST
1987 Ford Econoline E350, Van Window, 7.5 L

Open Field Or Short Circuit Test

1987 Ford Econoline E350, Van Window, 7.5 LSECTION Open Field Or Short Circuit Test
  1. Perform test before alternator disassembly. Adjust ohmmeter to x1 scale. Place ohmmeter leads on regulator "A" blade terminal and regulator "F" screw head. See Fig 1 . Rotate alternator pulley and note reading. Reverse ohmmeter leads and repeat test.
    Fig 1: Testing Field for Open or Short Circuit
    G15344Courtesy of FORD MOTOR CO.
  2. Reading should be between 2.2 and 100 ohms in one direction. Fluctuation may occur while pulley is turning. Reading should fluctuate between 2.2 and 9 ohms with leads reversed.
  3. Reading with approximately 9 ohms in one direction and no reading in the other indicates open brush lead, defective brushes or loose regulator-to-brush holder attaching screws.
  4. Reading of less than 2.2 ohms in both directions indicates a shorted rotor or defective regulator. Reading exceeding 9 ohms in both directions indicates a defective regulator or loose "F" terminal screw.
  5. Place one lead on alternator rear housing with remaining lead touching regulator "F" terminal. Note reading. Reverse leads and repeat test. Reading should be infinite in one direction and approximately 9 ohms with leads reversed.
  6. Reading less than infinite in both directions indicates a grounded brush lead or defective regulator. Reading exceeding 9 ohms in both directions indicates defective regulator or "A" terminal connection.
Fig 2: Exploded View of Integral Alternator/Regulator
G11717Courtesy of FORD MOTOR CO.
RENDER: 1.0x

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