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Home › Merkur › 1985 › XR4Ti Automatic › Repair and Diagnosis › Electrical › Charging Systems › Alternator - BOSCH › Testing (On-Vehicle) › Output Test

Output Test

  1. Check that connections at battery, alternator, and starter (most vehicles) are clean and tight. Check that alternator, engine and body are properly grounded. Check that alternator drive belt is tight and in good condition.
  2. Connect ammeter, following manufacturer's instructions. Connect voltmeter leads to battery terminals. Start engine and allow to idle. Adjust carbon pile until voltmeter reads 13.5 volts. Alternator output should be 28-35 amps.
  3. Repeat process at 1000 RPM. Alternator output should be 75-85 amps. Repeat test at 2000 RPM. Alternator output should be 89 amps. If alternator output is low, remove alternator for testing and repairs.
  4. Alternator output should equal alternator rated output, minus 16-20 amps. If reading is 16-20 amps below alternator rating, replace regulator and retest. If output is still too low, repair or replace alternator.
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