Automotive Electrical Systems Troubleshooting & Repair Basics

Problems with automotive electrical systems can have a number of causes. The adverse affects of weather are often to blame, as rain and splashed puddles can seep into cars and trucks, damaging circuitry. Perhaps the most common automotive electrical system failure is when a battery dies, which often requires the use of jumper cables to temporarily make the vehicle -- and its electrical components -- run again. When troubleshooting and repairing electrical problems, it is important to work cautiously and to get the help of an expert if necessary.

No Voltage

1. All of the electrical components in your car or truck require voltage in order to function. Therefore, according to AA1Car.com (see Reference 1), troubleshooting a malfunctioning automotive electrical system first requires you to test for voltage. You can use two tools to do this: a voltmeter or a 12-volt indicator light (that glows in the presence of voltage). No matter which you use, attach it to the malfunctioning component's voltage source or load point (such as a windshield wiper motor or light bulb). If there is no voltage detected at a load point, this is likely indicative of a blown fuse or a faulty circuit breaker. According to AA1Car.com, replacing a blown fuse will often restore power, but it will not be a permanent fix. You must determine the underlying cause of the blown fuse, which is likely a defective circuit breaker. According to the above source, the simplest way to check if a circuit breaker is functioning properly is to bypass it with the use of a jumper wire. If the electrical component functions when this happens, you will know the circuit breaker is faulty and needs replacing.

   Low Voltage

2. Automotive electrical components require not just voltage, but a specific quantity of voltage to function properly. Two common indications of low voltage are slower-starting engines and dimmer lights. According to AA1Car.com, a low battery could be the cause of low voltage in electrical components. You can use a voltmeter to test the battery, which should read at least 12.43 volts according to the above source. If your battery tests below this amount, recharge or replace it.
   Low voltage may also produce electric problems that occur only once in a while, such as the radio or air-conditioning cutting in and out. According to the above source, wiring resistance, such as a corroded or loose connector, usually causes this.
   To find the precise location of the problem, use a voltmeter to perform a drop test. This requires you to test consecutive sections of wiring, and look for drops in voltage. A voltage drop of more than .4 volts will indicate a problem area, according to AA1Car.Com.

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