Battery is Good, Alternator is good, both have been tested. My car starts up with no problem. when im driving in a neighborhood without having to apply alot of pressure on the gas everything is fine. But the moment i enter a freeway/highway where i have to press the gas a little harder my alternator fuse (30a) blows instantly as soons i begin to speed up the battery light comes on. I put another fuse in and same thing, everything is fine when im not pressing the gas hard but the moment i have to apply pressure my alternator fuse blows and the Battery comes on. So replcaed the fuse once again. This time i put some tape around my O2 Sensor wires. And wala! It worked, no fuse blowing when i speed up but then after like 15 min of driving it started back :/. What could be a possible fix?? thanks!!
Please let us know the make, model, year, and engine of your vehicle. The information may help us at this end. And did this problem appear all on its own? That is, was any work done to the car previous to this problem? What gave you the idea to put tape around your O2 sensor? It is very strange that it even had any effect on the situation. I find your problem very intriguing and would like very much to help you out. I'll return and edit this answer after you give us some more clues. Thanks for your cooperation. ---------------------------- Edit: As of this moment, you haven't given any more information. So I have to guess that although your alternator has been tested, it is likely not been tested as it would be stressed under the conditions that you have specified. I can only imagine that for some reason when under a high speed load, there is a condition in the alternator that causes excessive amperage to be drawn through the 30-amp fuse. A thorough inspection of the wiring to the alternator is also needed to rule out a short. Sorry to not be of more help. --------------------------------------- Edit: Did read your additional information. I checked for service bulletins. Although there were 126 of them, none of them dealt with this problem. The charging circuit was very simple and it looks as though the problem is internal to the alternator. Whatever test has been used is not covering the mode of operation that the alternator encounters in the vehicle. If individual components are available internal to the alternator, it can be the voltage regulator or possibly a rectifier. Often nowadays, the procedure is to replace the alternator altogether.
Alternator Fuse Keeps Blowing
Defective regulator/rectifier.
