M3 electrical problems, help?

[encasemyheart]

I seem to be having some electrical problems in the 99 M3.

Recently, all the dash lights in the car/radio/clock light etc. have been flickering along with my headlights. It's a noticible flicker, but they never lose power, just flicker.

It was doing this during the day the other day and I ended up turning on the headlights, which were off previously, and when I did so, the car turned off for a split second. It jerked, all the dash lights came on like when you first start the car and kept driving after that like normal. I could turn the headlights on/off no problems.

That same situation has happened a couple times and occasionally the ABS light will come on and stay on until the car is turned off.

Last night the whole system, including the headlights were flickering. I parked and when I turned the car back on, I had to input the radio code and time/date.

Yet another time, a few days ago, if I gave the car alot of throttle and got the revs up, it would do the thing like I just started the car, everything would freeese for a split second and the dash lights came on.

My first thought was alternator, but I dunno. Any ideas?

[Hammdy]

Yeah my first thought was alternator too. A failing alternator can make a car do weird things. But it could definately be something else too.

[M3andPorsche]

Previous write up:

I had some electrical issues lately which I thought were alternator, but turned out to be a loose cable. Check the negative battery cable in the trunk. My loosened up where it mounts to the body. I noticed the head lights and interior lights flickering. I watched the voltage (use OBC, see link below) while I drove and it was all over the place, from 15V to 11V. Also, using the OBC as voltmeter should tell you if your alternator is working or not. As, you drive the voltage should be a 14V + or - 0.2V. If it's 11V constantly while you are driving than your alternator is dead. If your voltage is constantly above 14.5 to 15V then your voltage regulator isn't working. And your alternator is over charging your battery and killing it. Finally, you should check the current draw while the car is off. To do this, you will need a multi-meter (radio shack, about $10). Disconnect the negative battery cable and place one lead on the negative battery terminal and the other on the battery cable. It should draw less than 50-75mA.

Let me know if you need any more help.



Link to use the OBC as a voltmeter:
http://ebaines.home.att.net/e36_obc.htm

[EastBayBimmer]

Sorry for bumping this old thread, but this is exactly what just started happening a few days ago. The ABS light comes on at random and stays lit until the car is restarted. While driving, all the lights flicker every once in a while, and sometimes enough that the radio restarts.

Im going to check the grounds, and the trunk wires tomorrow. Has anyone else experienced this and found a solution?