2008 Toyota Tundra Owners Manual - Page 215

07 11.20 Voltmeter The voltmeter tells whether the battery is charged or discharged. Check it while the engine is running-the needle should always indicate as shown above. Tachometer XS16007b Normal range Type A If the needle reads below or above the normal range while the engine is running, it indicates the charging system needs immediate repair. However, it is normal for the needle to drop below the normal range during engine starting. Type A XS16009 XS16008b Normal range Type B Type B XS16010 185 2008 TUNDRA from Apr. '08 Prod. (OM34477U)