If a malfunction occurs in the charging circuit, don't automatically assume the alternator is causing the problem. First check the following items: Check the drivebelt tension and condition. Replace it if it's worn or deteriorated. Make sure the alternator mounting and adjustment bolts are tight. Inspect the alternator wiring harness and the connectors at the alternator. They must be in good condition and tight. Check the fusible link (if equipped) located between the starter solenoid and alternator. If it's burned, determine the cause, repair the circuit and replace the link. Sometimes a fusible link may look good, but still be bad. If in doubt, remove it and check it for continuity. Start the engine and check the alternator for abnormal noises. Check the specific gravity of the battery electrolyte. If it's low, charge the battery. Make sure the battery is fully charged. Disconnect the battery cables. Inspect the battery posts and the cable clamps for corrosion. Clean them thoroughly if necessary. Reconnect the cable to the positive terminal. With the key off, connect a test light between the negative battery post and the disconnected negative cable clamp. If the test light doesn't come on, reattach the clamp. If the test light comes on, there's a short in the electrical system of the vehicle. The short must be repaired before the charging system can be checked. Disconnect the alternator wiring harness. If the light goes out, the alternator is bad. If the light stays on, pull each fuse until the light goes out. Using a voltmeter, check the battery voltage with the engine off. It should be approximately 12-volts. Further testing of this type of alternator must be done by a service station, dealer service department or auto electric shop. If the voltmeter indicates low battery voltage, the alternator is faulty and should be replaced with a new one or there is an open circuit between the alternator and the battery. If the voltage reading is 15-volts or higher and a no charge condition exists, the regulator or field circuit is the problem. Remove the alternator and have it checked by a service station, dealer service department or auto electric shop.
