Hi everyone
I have a very frustrating problem. I replaced the brake pads on all four wheels and when I went to pick my wife up from work I got the little battery light in the dash. Soon after the car lost power and stalled altogether. When I turned the key, the lights in the dash just flickered rapidly and the engine wouldn’t start. I went to get another car and by the time we got back the car started again. We got it back to the house in limp mode. We replaced the battery as it needed to be done anyway but a few days later the same problem appeared. I did some tests with a voltmeter and reaized that the battery is not being charged. I am not very good with electrical stuff but I assume it’s either the alternator or a bad ground wire. It seems too much of a coincidence that that alternator would go out right after me doing a brake job. So i’m thinking that maybe I damaged a ground wire or something while changing the brake pads. Is this possible? How should I proceed? Any help is much appreciated. Thank you everyone!

 

Brake pad replacements have nothing to do with the electrical system. There is not even a ground wire in any of the 4 wheel well that can cause electrical problems, unless you somehow shorted out the ABS sensor wires but I doubt it. All the ground wires are in the engine bay or behind the front bumper. It's just coincidence that your alternator died. Get your alternator replaced.

 

thank you for your quick response! It seemed crazy to me too. Wow what a coincidence then. I also did a voltmeter test by checking the batterys volts and then disconnecting the negative battery wire and holding the negative voltmeter probe to the disconnected negative wire and it showed a difference of 1 volt. This supposedly points to a bad ground somewhere. Is this not correct?

 

Bad ground (or bad connection is general) means high resistance connection. You check it by putting load on the system (bigger load, bigger current, bigger voltage difference due to the high resistance connection, etc.).

So if you want to check for bad ground, connect everything back together, put one probe on the lead battery negative terminal (not the clamp) and then other on some good body ground (for example around shock or engine itself) and then put some load on electrical system (engine off, car on, headlights on, blower motor on max). If you have high voltage difference, you have bad ground. In prefect world you want to see 0V.

Most likely you have bad alternator. To make sure that it's not a bad wire, check voltage between alternator housing and alternator positive terminal (hidden under rubber boot).Compare voltage with engine on, loads off and loads on.

To know more, check google or youtube for alternator testing.