GM Service Manual Online
For 1990-2009 cars only

The maintenance-free battery has a built-in hydrometer which consists of a ball floating in the electrolyte. The hydrometer is temperature-compensated. The color of the hydrometer indicates the condition of the battery.

    • A green dot appearing on the hydrometer means that the battery is ready for testing.
    • A dark hydrometer with no green visible means that the battery has a low charge. There may be a problem in the charging or electrical systems. Refer to Charging System Check or Battery Electrical Drain/Parasitic Load .
    • A clear or light yellow color means that the battery fluid level is below the bottom of the hydrometer. Replace the battery if the battery condition affects the cranking system. A low fluid level can be caused by any of the following conditions:
       - An excessive charge
       - Tipping the battery
       - A faulty charging system. Refer to Charging System Check .