LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Buick >> 1997 >> Century Custom >> Repair and Diagnosis >> Electrical >> Charging Systems >> On-Vehicle Testing >> Undercharged Or Overcharged Battery >> Notes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Undercharged Or Overcharged Battery: Notes

NOTE: Ensure battery is fully charged and in good condition before performing the following steps. If battery is not at (or near) a fully charged condition, service as necessary before proceeding.
  1. Turn ignition and all accessories off. Using a voltmeter, measure and record battery voltage for use in step 4). Disconnect generator harness connector. Turn ignition switch to ON position (engine not running).
  2. Connect negative lead of a voltmeter to a good engine ground. Connect positive voltmeter lead to terminal "L" of generator harness connector. On models with gauges, also connect positive voltmeter lead to terminal F/I of generator harness connector. See WIRING DIAGRAM .
  3. Battery voltage should be present at terminal "L" or F/I (gauges only). If battery voltage is not present, repair open circuit between generator connector terminal and battery. If battery voltage is present, reconnect generator harness connector and go to next step.
  4. Start engine and slowly increase speed to approximately 1500 RPM. Using a voltmeter, measure voltage between battery terminals. If voltage is greater than 16 volts, or less than voltage as measured in step 1), replace or repair generator. If voltage is less than 16 volts, or greater than voltage as measured in step 1), go to next step.
    CAUTION: To prevent injury and/or damage to vehicle, disconnect negative battery cable before connecting or disconnecting a series type ammeter to generator.
    CAUTION: Carbon pile testing is part of this procedure. To avoid battery explosion, turn carbon pile OFF before connecting to or disconnecting from vehicle battery.
  5. Disconnect negative battery cable. Install ammeter to voltmeter. Connect voltmeter to generator output (BAT) terminal. Connect negative battery cable. With load off, connect carbon pile load tester across battery terminals. Run engine at approximately 1500 RPM, turn accessories on and load battery with carbon pile load until maximum generator output is reached. Adjust carbon pile to maintain 13 volts or more. Measure amp output.
  6. If amp output is within 15 amps of rated output, generator is okay. If amp output is not within 15 amps of rated output, repair or replace generator. See GENERATOR USAGE/AMP OUTPUT RATING  table.
scientia non olet · About LEMON Manuals