Alternator sudden death?
 

I have a 1981 240d 4speed. For awhile now the battery light has been bright red at idle and then it goes away when you hit the throttle, makes me think its the alternator. But suddenly a few days ago. i have Bright red battery light at idle and at full speed along with the brake pad indicator. I checked voltage at the battery, it was steady at 12.4 volts and didnt increase with rpm. what could this be? i allready replaced the voltage regulator a few months ago. and i made sure the ground strap was good along with all other connections. Where is the fuse for this thing at?

Check the wires going from the alternator to the starter post.

Will do, thanks.

In normal operation, you should not see the battery light come on even at idle. Did this behavior show itself before you replaced the regulator a while back?

I think you may have blown the voltage regulator again. This might happen due to bad electrical connections. It is possible the interior electrical connections in your alternator, that the voltage regulator presses up against, have corroded.

So I think you have two issues now, voltage regulator and a bad connection somewhere. If you don't find anything external to the alternator, you may be looking at trying to clean up your existing alternator, or going with a rebuild.

The other thing that might cause poor charging at idle is a blown rectifier diode. These are not easily replaced. When you have a blown diode, it usually causes a lot more electrical noise on the radio - but not necessarily depending on the quality of the filtering in the radio.

If no external connection problem, you can probably solve your issues the fastest with a rebuilt unit.

Ken300D

Your voltage regulator was probably extremely worn, and then finally died completely or the brushes are no longer touching the slip rings....on mine it was putting out almost no power, upon inspection when I removed it, the slip rings had deep grooves, and the brushes were very worn down (and had grooves in them). New alternator fixed the issue.

Read carefully grass hoppa.........;)