Battery System

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 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 interde-pendency 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), a 12-volt test lamp and/or special service tools 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. Always check the PCM for stored trouble codes before returning the vehicle to service. Refer to Charging System for the proper charging system test procedures. Refer to Starting System for the proper starting system test procedures.

MICRO 420 BATTERY TESTER
The Micro 420 automotive battery tester is designed to help the dealership technician diagnose a defective battery. Follow the instruction manual supplied with the tester to properly diagnose a battery. If the instruction manual is not available, refer to the standard procedure, which includes the directions for using the Micro 420 battery tester.

Battery System Diagnosis Part 1:

Battery System Diagnosis Part 2:

ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnormal battery discharging:
1. A faulty or incorrect charging system component. Refer to Charging System for additional charging system diagnosis and testing procedures.
2. A faulty or incorrect battery. Use Micro 420 battery tester and refer to Battery System for additional battery diagnosis and testing procedures.
3. A faulty circuit or component causing excessive ignition-off draw.
4. Electrical loads that exceed the output of the charging system. This can be due to equipment installed after manufacture, or repeated short trip use.
5. A faulty or incorrect starting system component. Refer to Starting System for the proper starting system diagnosis and testing procedures.
6. Corroded or loose battery posts and/or terminal clamps.
7. Slow driving speeds (heavy traffic conditions) or prolonged idling, with high-amperage draw systems in use.