Troubleshooting Car Electrical Problems

Troubleshooting car electrical problems can be a lot of fun, if you are a do-it-yourself kind of a guy, who enjoys solving mysteries and is in love with his car! In order to fix car problems, you need not be an automobile engineer. For solving car electrical problems, all you need is a fundamental understanding of the Ohm's law and a detailed circuit diagram of your car's electrical circuitry. The electrical circuit network of a car, serves as the control and powering mechanism for all the working systems of the car. Let us understand how to diagnose and troubleshoot car electrical problems.

Car Electrical Troubleshooting Precautions

The typical voltage range in car electric circuitry is around 10-16 V. Therefore the likelihood of getting an electric shock is very less, unless you are tampering with the ignition assembly of any car or the battery system of a hybrid car. Refer to circuit diagram of electrical assembly before disconnecting any wire connections or making new ones. Check and keep track of the colors of the wires and keep in mind the important details of which one goes where! Disconnect the battery when replacing or removing any electrical components. This eliminates the risk of any components inadvertently being shorted and the PCM (Power train Control Module) of the car being damaged.

Diagnostic Principles and Tools of Car Electrical Troubleshooting

The diagnostic tools for troubleshooting car electrical problems are an ohmmeter to measure resistance, a voltmeter, both with attached leads and a discerning intellect! You may also use a 12 volt light tester for a quick check but its better to have a voltmeter to get accurate voltage readings.

The principles of diagnosing a car electric problem is the Ohm's law. Voltage is directly proportional to current for a solid conductor and the proportionality constant is the resistance of the circuit!

Remember that every device needs electric power for its functioning and there is a minimum threshold voltage, that is absolutely necessary for its operation. So the diagnostic method is simply measuring the voltages at various load points of the car. Load points are contact points where power is supplied to a load which could be the car light bulb, the windshield wiper, the ignition assembly or any other working car part, which is showing problems. Therefore, if the voltage levels at any of these points are abnormal, then you can be sure that there is a problem. Thus most car electrical problems are essentially low voltage problems, 'no voltage' problems, excess resistance problems or circuit discontinuity problems. In some cases the problem may also be, due to burning out of some components.

Troubleshooting

The first place to check for car electrical problems is the car battery. If the battery itself is not giving the required output voltage, then every component associated with it shows problems. So to check the battery output first, disconnect it from the car connections. The PCM may get reset and lose its programmed settings when the battery power is disconnected. So attach a 9 V battery to the PCM to avoid this.

Then measure the voltages between the output leads of the battery. If the voltage reading is equal to or in excess of 12.43 V, your battery is charged sufficiently enough and is working. If the voltage is around 12.66 volts, your battery is fully charged and you have no reason to worry. If it is less than 12.43 V, the the battery needs charging.

Next reconnect the battery and check voltage of load points of the car devices which are not working properly. If the voltage is zero or very low at a particular point, there are many possible case scenarios. One possibility is that the fuse that protects the device has burned out or secondly the relay that switches power to that part has stopped working. Check and replace these if you find them faulty. Next check the grounding at that point. A car circuitry is grounded in the metal body of the car itself. If the grounding is at fault, current conduction is not possible. If that is the problem, then fix it by grounding the terminal from that point.

If the fuses are in place, grounding is sound and the relays are working properly, then a third reason for the low or zero voltage could be corroded wires or wires with discontinuity. Checking for corroded wires is done by checking the voltage drop across them. If the voltage difference between two connected points of the wire shows a voltage drop of more than 0.1 Volts, there is a problem. You must replace the wire. The method for checking continuity is to measure resistance between the points, connected by the wire using an ohmmeter. If its infinite, the wire has broken inside and must be replaced.

If neither the fuses, relays or wires show a problem and the devices are not working, then you can safely conclude that there is problem with the end device. Water exposure of an electrical circuit can lead to such shorting of devices. Water seepage into windshield wiper circuitry or other circuitry is common during the rainy season.

Performing a periodic check of the car's electrical installations in this way, prevents any future problems that may crop up. Changing and replacing components and making a full scale car repair could be a job, best left to a mechanic but understanding and diagnosing the electrical problem could be done by you. Hope I have succeeded in conveying to you, what a humble man armed with a voltmeter and an ohmmeter can achieve! Troubleshooting car electrical problems this way, not only introduces you to the amazing intricacies of car design, but also gives you the satisfaction of solving a problem on your own!