89 honda accord dx manual...All of a sudden my battery light came on and the engine is racing between 3 and 4 thousand rpm in neutral and knocks when I try to turn it off...any ideas...is my alternator gone..is the engine racing related to alternator failure somehow...?

 

The electric choke stays closed when there isn't enough voltage from the alternator. That is the probable cause of the fast idle.
You can try smacking the Alt a few times and if that makes the light go out, you'll need a new brush pak. Most Honda parts or auto electric shops have them on hand. You can replace the brush pak without removing the alt. completely from the car. Because to get that Alt all the way to a bench requires the drivers side axle be removed. the brush pak is under the tin shroud on the back of the alt, take the drive belt loose then remove the top bolt [don't lose the spacer washer behind the swivel bracket], then swivel the alt on it's bottm bolt. unhook the battery then remove the battery cable from the Alt. next remove the 10mm nut under the battery cable and pull out the insulator. there are 3- 8mm nuts on the back of the alt that hold the cover on; when the cover is out of the way you'll be able to see 2 phillips head screws holding the brush pak on. BE SURE to use a good fitting phillips bit to get those loose. When re-installing the new brush pak use a thin feeler gauge to get the new brushes to slip over the armature.

 

you can have the battery and alternator checked by some autoparts stores. autozone being one of them...