GM Service Manual Online
For 1990-2009 cars only

    Caution: Refer to Batteries Produce Explosive Gases Caution in the Preface section.

  1. Check the battery for obvious damage, such as a cracked or broken case or cover, which could permit the loss of electrolyte. If obvious damage is noted, replace the battery.
  2. Caution: Do not charge the battery if the hydrometer is clear or light yellow color. The battery must be replaced. Charging the battery in this state could result in personal injury or vehicle damage.

  3. Check the hydrometer. If the green dot is visible, go to the load test procedure. If the indicator is dark but green is not visible, charge the battery. For charging a battery removed from the vehicle, refer to Charging System Test .
  4. Connect a voltmeter and a battery load tester across the battery terminals.
  5. Apply a 300-ampere load for 15 seconds to remove any surface charge from the battery.
  6. Remove the load.
  7. Wait 15 seconds to let the battery recover, and apply a 270-ampere load.
  8. Important: The battery temperature must be estimated by touch and by the temperature condition. The battery had been exposed for the preceding few hours.

  9. If the voltage does not drop below the minimum listed, the battery is good and should be reinstalled. If the voltage is less than the minimum listed, replace the battery. Refer to Battery Usage