The battery, starting, and charging systems in the vehicle operate with one another and must be tested as a complete system. In order for the engine to start and the battery to maintain its charge properly, all of the components that are used in these systems must perform within specifications. It is important that the battery, starting, and charging systems be thoroughly tested and inspected any time a battery needs to be charged or replaced. The cause of abnormal battery discharge, overcharging or early battery failure must be diagnosed and corrected before a battery is replaced and before a vehicle is returned to service. The service information for these systems has been separated within this service manual to make it easier to locate the specific information you are seeking. However, when attempting to diagnose any of these systems, it is important that you keep their interdependency in mind.The diagnostic procedures used for the battery, starting, and charging systems include the most basic conventional diagnostic methods, to the more sophisticated On-Board Diagnostics (OBD) built into the Powertrain Control Module (PCM). Use of an induction-type milliampere ammeter, a volt/ohmmeter, a battery charger, a carbon pile rheostat (load tester) and a 12-volt test lamp may be required. All OBD-sensed systems are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for any failure it detects. (Refer to 8 - ELECTRICAL/CHARGING - DIAGNOSIS AND TESTING) for the proper charging system on-board diagnostic test procedures.The Micro 420 automotive battery tester is designed to help diagnose the cause of a defective battery. Follow the instruction manual supplied with the tester to properly diagnose a vehicle. If the instruction manual is not available, (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BATTERY - STANDARD PROCEDURE - USING MICRO 420 BATTERY TESTER) which includes the directions for using the Micro 420 battery tester.The OTC One Step Battery Analyzer and Charger is designed to help diagnose the cause of a defective battery. Follow the instruction manual supplied with the tester to properly diagnose a vehicle.BATTERY SYSTEM DIAGNOSISCONDITIONPOSSIBLE CAUSESCORRECTIONTHE BATTERY SEEMS WEAK OR DEAD WHEN ATTEMPTING TO START THE ENGINE.1. The electrical system ignition-off draw is excessive.1. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BATTERY - STANDARD PROCEDURE - IGNITION-OFF DRAW TEST) for the appropriate test procedures. Repair the excessive ignition-off draw, as required.2. The charging system is inoperative.2. Determine if the charging system is performing to specifications. (Refer to 8 - ELECTRICAL/CHARGING - DIAGNOSIS AND TESTING) for the appropriate charging system diagnosis and testing procedures. Repair the inoperative charging system, as required.3. The battery is discharged.3. Determine the battery state-of-charge using the appropriate battery tester. Charge the inoperative battery, as required.4. The battery terminal connections are loose or corroded.4. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/CABLES - DIAGNOSIS AND TESTING) for the appropriate battery cable diagnosis and testing procedures. Clean and tighten the battery terminal connections, as required.5. The battery has an incorrect size or rating for this vehicle.5. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM - SPECIFICATIONS) for the proper battery size and rating. Replace an incorrect battery, as required.6. The battery is inoperative.6. Test the battery using the appropriate battery tester. Replace the inoperative battery, as required.7. The starting system is inoperative.7. Determine if the starting system is performing to specifications. (Refer to 8 - ELECTRICAL/STARTING - SPECIFICATIONS). Repair the inoperative starting system, as required.8. The battery is physically damaged.8. Inspect the battery for loose terminal posts or a cracked and leaking case. Replace the damaged battery, as required.THE BATTERY STATE OF CHARGE CANNOT BE MAINTAINED.1. The battery has an incorrect size or rating for this vehicle.1. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM - SPECIFICATIONS) for the proper battery size and rating. Replace an incorrect battery, as required.2. The battery terminal connections are loose or corroded.2. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/CABLES - DIAGNOSIS AND TESTING) for the appropriate battery cable diagnosis and testing procedures. Clean and tighten the battery terminal connections, as required.3. The electrical system ignition-off draw is excessive.3. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BATTERY - STANDARD PROCEDURE - IGNITION-OFF DRAW TEST) for the appropriate test procedures. Repair the excessive ignition-off draw, as required.4. The battery is inoperative.4. Test the battery using the appropriate battery tester. Replace the inoperative battery, as required.5. The starting system is inoperative.5. Determine if the starting system is performing to specifications. (Refer to 8 - ELECTRICAL/STARTING - SPECIFICATIONS). Repair the inoperative starting system, as required.6. The charging system is inoperative.6. Determine if the charging system is performing to specifications. (Refer to 8 - ELECTRICAL/CHARGING - DIAGNOSIS AND TESTING) for the appropriate charging system diagnosis and testing procedures. Repair the inoperative charging system, as required.7. Electrical loads exceed the output of the charging system.7. Inspect the vehicle for aftermarket electrical equipment which might cause excessive electrical loads.8. Slow driving or prolonged idling with high-amperage draw loads in use.8. Advise the vehicle operator, as required.THE BATTERY WILL NOT ACCEPT A CHARGE.1. The battery is inoperative.1. Test the battery using the appropriate battery tester. Replace the inoperative battery, as required.