Component Tests: Tachometer

Connect test tachometer to ignition coil. Start engine. Compare vehicle tachometer reading with test tachometer reading. Vehicle tachometer reading must be within allowable range when ambient temperature is between -4°F to 140°F (-20°C to 60°C) and battery voltage is 10-15 volts. See TACHOMETER VARIATION SPECIFICATIONS  table. If tachometer reading is not within specifications, replace tachometer.