It all starts with a handful of telltale problems. A growling noise under the hood, headlight bulbs blowing out repeatedly, dimming headlights, an out of range dash voltmeter and at times, an odd smell.
While most people tend to overlook some of these indications, alternator problems can cause vehicle trouble ranging from slow starts all the way to a dead vehicle if not promptly attended to.
If you are experiencing any of these problems, here are some helpful tips that will help you troubleshoot your vehicle’s alternator charging system.
1- Conduct a Visual Inspection Under the Hood
Inspect belt condition and tension. Ensure it’s not worn, cracked, loose, or glazed. If that checks out, examine the electrical connections and cables for signs of corrosion and proper firmness. Lastly, ensure the alternator is correctly fixed.
2- Visually Inspect and Test the Batteries
Examine the batteries for any indication of physical damage, broken casing, unfastened terminals, or dripping fluid. If you encounter any of these signs, clean, repair the connection, and change any damaged batteries found. It is, however, important to keep in mind that all the batteries used in the circuit are of the same age, cold cranking amps (CCA) rating, and from the same manufacturer.
Next, carry out a battery test using the standard battery test method. Bear in mind that for realistic testing as well as successful operation, you will require a completely charged battery that will be able to supply the starting system’s needs.
3- Perform a System Voltage Test
The other step to troubleshoot the alternator charging system is to measure the voltage of the battery while the engine is running using a voltmeter for accurate results. If the recorded voltage is higher or equal to 13.8 volts, you can test the alternator output.
However, if the voltage is less than 13.8, determine the voltage at alternator B+ and the alternator ground case. Keep in mind that if the model is insulated, you have to use a ground stud to get a reading. In addition, if the alternator has remote sense, the voltage at the alternator could be more than 15 volts.
Now, if the voltage is between 12.6V and 13.7V, its time you change your alternator. However, if the voltage is greater or equal to 13.8, perform a voltage drop test.
4- Test Alternator Output
Performing an alternator load test ensures that the alternator is providing sufficient current for operating the vehicle’s electrical loads and maintaining battery charge. To perform alternator output test, you can employ the automated tester method or the manual process. To perform the manual process, you will need a Carbon Pile tester, an Ammeter, and an Amp Clamp.
First connect the carbon pile tester to the battery; the positive or red lid connects to the positive post and the negative or black lid to the negative post on the battery. Then clamp the ammeter in the correct polarity around the B+ cable near the alternator.
Now with the engine running at governor speed and all electrical loads turned off increase the load of the carbon pile until the ammeter reads its highest value, record the output and turn off the carbon pile and engine. Amp output should be at least 90% of the rated capacity. If it’s not, that is a clear sign that the alternator needs to replacement.
Troubleshooting Using Service Manual
If you have conducted all the four steps laid down above, the problem might be due to something external.
For more information on alternators, please visit www.elreg.com.