0 rpms when Alternator goes out?

[graphikg]

I was just on my monday morning drive to work when I notice that all my dash lights are very very dim. I thought this was odd so just to experiment, I turn on the headlights and..... BAM! the car shoots the rpm meter down to zero. Very quickly, I turn the lights back off, and back up they go to 3000rpm (freeway speed). I thought it was the alternator so after all this hassle of driving back home, I replaced the alternator with the one in my S50 swapped e30 and went back to work. What a day...

But are these the symptoms from a bad alternator? And can it happen while on the freeway?

Update: And now since the alternator is in, and the battery is back at full power, my dual sunroof doesnt work. Whats wrong with that?

[David325e]

Probably need to reset the sunroof computer. Something about holding the switch in the closed position or something. Search, and start with the oldest threads and work your way forward.

When my alternator went while driving on the highway (has also happened in town haha) I noticed it because my tach was working but I was flying past cars. Finally figured out that the car wasn't making enough power to put the speedo above 50. And I had to choose between steering or brakes. Power steering died when I hit the brakes. And when it died in town I had to cut the lights to accelerate up hills. Did the car do the same thing with the new alt? And yea if a car dies while running its the alt. Good alt can keep the car running, battery does the cranking.

[graphikg]

Nice, I think you answered all questions :). I will check the sunroof mechanism on the search. Now that the alt is replaced, the car seems to be acting normal, and not throwing the "trans program."

[David325e]

Trans prog comes on when car gets below 4.4Vs. Thats not too far from backfiring. Do test 19 and see what you're getting at the alt, do the terminal tests etc. Sounds like you're good. Did you also have flickering lights and things like radio lowering?