Battery, Ignition and On-Board Diagnostics

To keep an automobile up and running, diagnostic procedures must be conducted on a regular basis. While most testing is done to ensure soundness of the engine, it is significant to examine the battery, ignition and on-board systems as well. Failure of any of these critical components leads to a complete vehicle breakdown and loss of valuable time and money.

Battery Diagnostics

Increasing complexity in automotive systems leads to rising demand for electrical power. In turn, this leads to greater demands on the battery of the vehicle. Regardless of the automobile being electric or dependent on an internal combustion engine, ensuring battery reliability is of utmost importance. This requires regular monitoring of battery diagnostics while the automobile is running.

Since a battery discharges even when not in active use, its health deteriorates over time. Battery diagnostics helps in identifying a depleted or faulty battery, thus avoiding a system breakdown.

The latest approach to conducting battery diagnostics is measuring its state of charge in terms of current-delivery capacity and its state of health in terms of the remaining percentage of battery life while the vehicle, with its various electrical loads, is in operation.

Ignition Diagnostics

A timing light is used to set the ignition timing of a vehicle. When it is attached to the ignition circuit while the engine is running, it identifies timing marks, thus enabling setting the timing of the ignition system.

To do this, the test probes of the timing light should be connected with the battery terminals in congruence with their polarities. When its trigger is pulled, the timing light releases a beam every time the sparkplug fires.

Traditional timings lights consist of two test probes, of which one is clamped to the battery ground and the other is inserted between the distributor cap and the sparkplug wire. The spark of the ignition itself powers these low-cost timing lights. Since they use a neon bulb, they are not very bright and are useful only in dimly lit utility areas. Since newer cars are composed of direct ignition systems, timing lights powered by direct current are preferred.

On-Board Diagnostics

Repair technicians may plug automotive scan tools into the on-board diagnostics (OBD) connector to access functions that give information on the condition of the various sub-systems in the vehicle. Mechanics rely on these tools to diagnose the specific error that causes a failure in the system.

Automotive scan tools may be handheld or PC-based. Handheld ones for consumers include simple fault code readers and reset tools. For professionals, these tools access advanced diagnostics and control units, set ECU parameters specific to the manufacturer or vehicle and facilitate diagnosis or tuning by performing real-time monitoring and graphing of engine parameters.

More advanced, PC-based automotive scan tools convert OBD-II signals into serial data compatible for display on standard personal computers. These automotive scan tools offer larger storage capacity, higher screen resolution and better flexibility than handheld ones.

Originally, testing tools were bulky and affordable only for very big garages. The last decade has seen increased portability and cost-effectiveness, putting them in reach of even the smallest automotive repair service.